Printable Composition of a Liquid or Gel Suspension of Diodes

ABSTRACT

An exemplary printable composition of a liquid or gel suspension of diodes comprises a plurality of diodes, a first solvent and/or a viscosity modifier. In other exemplary embodiments a second solvent is also included, and the composition has a viscosity substantially between about 100 cps and about 25,000 cps at about 25° C. In an exemplary embodiment, a composition comprises: a plurality of diodes or other two-terminal integrated circuits; one or more solvents comprising about 15% to 99.9% of any of N-propanol, isopropanol, dipropylene glycol, diethylene glycol, propylene glycol, 1-methoxy-2-propanol, N-octanol, ethanol, tetrahydrofurfuryl alcohol, cyclohexanol, and mixtures thereof; a viscosity modifier comprising about 0.10% to 2.5% methoxy propyl methylcellulose resin or hydroxy propyl methylcellulose resin or mixtures thereof; and about 0.01% to 2.5% of a plurality of substantially optically transparent and chemically inert particles having a range of sizes between about 10 to about 50 microns.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of and claims priority to U.S. patentapplication Ser. No. 13/223,279, filed Aug. 31, 2011, inventors MarkDavid Lowenthal et al., entitled “Printable Composition of a Liquid orGel Suspension of Diodes”, which is a nonprovisional of and claims andpriority to U.S. Provisional Patent Application No. 61/379,225, filedSep. 1, 2010, inventors William Johnstone Ray et al., entitled“Printable Composition of a Liquid or Gel Suspension of Diodes”, whichis commonly assigned herewith, the entire contents of which areincorporated herein by reference with the same full force and effect asif set forth in their entirety herein, and with priority claimed for allcommonly disclosed subject matter.

U.S. patent application Ser. No. 13/223,279 also is a nonprovisional ofand claims the benefit of and priority to U.S. Provisional PatentApplication No. 61/379,284, filed Sep. 1, 2010, inventors WilliamJohnstone Ray et al., entitled “Light Emitting, Photovoltaic and OtherElectronic Apparatus”, which is commonly assigned herewith, the entirecontents of which are incorporated herein by reference with the samefull force and effect as if set forth in their entirety herein, and withpriority claimed for all commonly disclosed subject matter.

U.S. patent application Ser. No. 13/223,279 also is a nonprovisional ofand claims the benefit of and priority to U.S. Provisional PatentApplication No. 61/379,830, filed Sep. 3, 2010, inventors WilliamJohnstone Ray et al., entitled “Printable Composition of a Liquid or GelSuspension of Diodes and Method of Making Same”, which is commonlyassigned herewith, the entire contents of which are incorporated hereinby reference with the same full force and effect as if set forth intheir entirety herein, and with priority claimed for all commonlydisclosed subject matter.

U.S. patent application Ser. No. 13/223,279 also is a nonprovisional ofand claims the benefit of and priority to U.S. Provisional PatentApplication No. 61/379,820, filed Sep. 3, 2010, inventors WilliamJohnstone Ray et al., entitled “Light Emitting, Photovoltaic and OtherElectronic Apparatus”, which is commonly assigned herewith, the entirecontents of which are incorporated herein by reference with the samefull force and effect as if set forth in their entirety herein, and withpriority claimed for all commonly disclosed subject matter.

U.S. patent application Ser. No. 13/223,279 is a continuation-in-part ofand claims priority to U.S. patent application Ser. No. 11/756,616,filed May 31, 2007, inventors William Johnstone Ray et al., entitled“Method of Manufacturing Addressable and Static Electronic Displays”,which is commonly assigned herewith, the entire contents of which areincorporated herein by reference with the same full force and effect asif set forth in their entirety herein, and with priority claimed for allcommonly disclosed subject matter.

U.S. patent application Ser. No. 13/223,279 is a continuation-in-part ofand claims priority to U.S. patent application Ser. No. 12/601,268,filed Nov. 22, 2009 and now abandoned, inventors William Johnstone Rayet al., entitled “Method of Manufacturing Addressable and StaticElectronic Displays, Power Generating and Other Electronic Apparatus”,which is a continuation-in-part of and claims priority to U.S. patentapplication Ser. No. 11/756,616, filed May 31, 2007, inventors WilliamJohnstone Ray et al., entitled “Method of Manufacturing Addressable andStatic Electronic Displays”, and which is a U.S. National Phaseapplication under 35 U.S.C. Section 371 of and claims priority tointernational application PCT/US2008/65237, filed May 30, 2008,inventors William Johnstone Ray et al., entitled “Method ofManufacturing Addressable and Static Electronic Displays, PowerGenerating and Other Electronic Apparatus”, which claims priority toU.S. patent application Ser. No. 11/756,616, filed May 31, 2007, whichare commonly assigned herewith, the entire contents of which areincorporated herein by reference with the same full force and effect asif set forth in their entireties herein, and with priority claimed forall commonly disclosed subject matter.

U.S. patent application Ser. No. 13/223,279 also is acontinuation-in-part of and claims priority to U.S. patent applicationSer. No. 13/149,681, filed May 31, 2011 and now abandoned, inventorsWilliam Johnstone Ray et al., entitled “Addressable or Static LightEmitting or Electronic Apparatus”, which is a continuation of and claimspriority to U.S. patent application Ser. No. 11/756,619, filed May 31,2007 and issued Jul. 5, 2011 as U.S. Pat. No. 7,972,031 B2, inventorsWilliam Johnstone Ray et al., entitled “Addressable or Static LightEmitting or Electronic Apparatus”, which are commonly assigned herewith,the entire contents of which are incorporated herein by reference withthe same full force and effect as if set forth in their entiretiesherein, and with priority claimed for all commonly disclosed subjectmatter. U.S. patent application Ser. No. 13/223,279 is acontinuation-in-part of and claims priority to U.S. patent applicationSer. No. 12/601,271, filed Nov. 22, 2009, inventors William JohnstoneRay et al., entitled “Addressable or Static Light Emitting, PowerGenerating or Other Electronic Apparatus”, which is acontinuation-in-part of and claims priority to U.S. patent applicationSer. No. 11/756,619, filed May 31, 2007, inventors William Johnstone Rayet al., entitled “Addressable or Static Light Emitting or ElectronicApparatus”, and which is a U.S. National Phase application under 35U.S.C. Section 371 of and claims priority to international applicationPCT/US2008/65230, filed May 30, 2008, inventors William Johnstone Ray etal., entitled “Addressable or Static Light Emitting, Power Generating orOther Electronic Apparatus”, which claims priority to U.S. patentapplication Ser. No. 11/756,619, filed May 31, 2007, which are commonlyassigned herewith, the entire contents of which are incorporated hereinby reference with the same full force and effect as if set forth intheir entireties herein, and with priority claimed for all commonlydisclosed subject matter.

U.S. patent application Ser. No. 13/223,279 also is related to thefollowing patent applications filed concurrently therewith, which arecommonly assigned herewith, the entire contents of which areincorporated herein by reference with the same full force and effect asif set forth in their entireties herein, and with priority claimed forall commonly disclosed subject matter: (1) U.S. patent application Ser.No. 13/223,289, filed Aug. 31, 2011, inventors Mark D. Lowenthal et al.,entitled “Light Emitting, Power Generating or Other ElectronicApparatus”; (2) U.S. patent application Ser. No. 13/223,286, filed Aug.31, 2011, inventors Mark D. Lowenthal et al., entitled “Method ofManufacturing a Printable Composition of a Liquid or Gel Suspension ofDiodes”; (3) U.S. patent application Ser. No. 13/223,293, filed Aug. 31,2011, inventors Mark D. Lowenthal et al., entitled “Method ofManufacturing a Light Emitting, Power Generating or Other ElectronicApparatus”; (4) U.S. patent application Ser. No. 13/223,297, filed Aug.31, 2011 and issued Apr. 9, 2013 as U.S. Pat. No. 8,415,879, inventorsMark D. Lowenthal et al., entitled “Diode For a Printable Composition”;(5) U.S. patent application Ser. No. 13/223,294, filed Aug. 31, 2011 andissued Mar. 18, 2014 as U.S. Pat. No. 8,674,593, inventors Mark D.Lowenthal et al., entitled “Diode For a Printable Composition”; and (6)U.S. patent application Ser. No. 13/223,302, filed Aug. 31, 2011,inventors Mark D. Lowenthal et al., entitled “Printable Composition of aLiquid or Gel Suspension of Two-Terminal Integrated Circuits andApparatus”.

COPYRIGHT NOTICE AND PERMISSIONS

A portion of the disclosure of this patent document contains materialwhich is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure, as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightrights whatsoever. The following notice shall apply to this document,the data and contents as described below, and the drawings hereto:Copyright© 2010-2011, NthDegree Technologies Worldwide, Inc.

FIELD OF THE INVENTION

The present invention in general is related to light emitting andphotovoltaic technology and, in particular, is related to a compositionof light emitting or photovoltaic diodes or other two-terminalintegrated circuits suspended in a liquid or gel and capable of beingprinted, and methods of manufacturing a composition of light emitting,photovoltaic or other diodes or two-terminal integrated circuitssuspended in a liquid or gel.

BACKGROUND OF THE INVENTION

Lighting devices having light emitting diodes (“LEDs”) have typicallyrequired creating the LEDs on a semiconductor wafer using integratedcircuit process steps. The resulting LEDs are substantially planar andcomparatively large, on the order of two hundred or more microns across.Each such LED is a two terminal device, typically having two metallicterminals on the same side of the LED, to provide Ohmic contacts forp-type and n-type portions of the LED. The LED wafer is then dividedinto individual LEDs, typically through a mechanical process such assawing. The individual LEDs are then placed in a reflective casing, andbonding wires are individually attached to each of the two metallicterminals of the LED. This process is time consuming, labor intensiveand expensive, resulting in LED-based lighting devices which aregenerally too expensive for many consumer applications.

Similarly, energy generating devices such as photovoltaic panels havealso typically required creating the photovoltaic diodes on asemiconductor wafer or other substrates using integrated circuit processsteps. The resulting wafers or other substrates are then packaged andassembled to create the photovoltaic panels. This process is also timeconsuming, labor intensive and expensive, resulting in photovoltaicdevices which are also too expensive for widespread use without beingsubsidized by third parties or without other governmental incentives.

Various technologies have been brought to bear in an attempt to createnew types of diodes or other semiconductor devices for light emission orenergy generation purposes. For example, it has been proposed thatquantum dots, which are functionalized or capped with organic moleculesto be miscible in an organic resin and solvent, may be printed to formgraphics which then emit light when the graphics are pumped with asecond light. Various approaches for device formation have also beenundertaken using semiconductor nanoparticles, such as particles in therange of about 1.0 nm to about 100 nm (one-tenth of a micron). Anotherapproach has utilized larger scale silicon powder, dispersed in asolvent-binder carrier, with the resulting colloidal suspension ofsilicon powder utilized to form an active layer in a printed transistor.Yet another different approach has used very flat AlInGaP LEDstructures, formed on a GaAs wafer, with each LED having a breakawayphotoresist anchor to each of two neighboring LEDs on the wafer, andwith each LED then picked and placed to form a resulting device.

Other approaches have used “lock and key” fluidic self-assembly, inwhich trapezoidal-shaped diodes have been placed in a solvent, and thenpoured over a substrate having matching, trapezoidal-shaped holes tocatch and hold the trapezoidal-shaped diodes in place. Thetrapezoidal-shaped diodes in the solvent, however, are not suspended anddispersed within the solvent. The trapezoidal-shaped diodes insteadsettle out rapidly into clumps of diodes adhering to each other, areunable to be maintained in a suspension or otherwise dispersed withinthe solvent, and require active sonication or stirring immediatelybefore use. Such trapezoidal-shaped diodes in a solvent cannot beutilized as a diode-based ink capable of being stored, packaged orotherwise used as an ink, and further are unsuitable for use in aprinting process.

None of these approaches have utilized a liquid or gel containingtwo-terminal integrated circuits or other semiconductor devices whichare actually dispersed and suspended in the liquid or gel medium, suchas to form an ink, with the two-terminal integrated circuits suspendedas particles, with the semiconductor devices being complete and capableof functioning, and which can be formed into an apparatus or system in anon-inert, atmospheric air environment, using a printing process.

These recent developments for diode-based technologies remain toocomplex and expensive for LED-based devices and photovoltaic devices toachieve commercial viability. As a consequence, a need remains for lightemitting and/or photovoltaic apparatuses which are designed to be lessexpensive, in terms of incorporated components and in terms of ease ofmanufacture. A need also remains for methods to manufacture such lightemitting or photovoltaic devices using less expensive and more robustprocesses, to thereby produce LED-based lighting devices andphotovoltaic panels which may be available for widespread use andadoption by consumers and businesses. Various needs remain, therefore,for a liquid or gel suspension of completed, functioning diodes or othertwo-terminal integrated circuits which is capable of being printed tocreate LED-based devices and photovoltaic devices, for a method ofprinting to create such LED-based devices and photovoltaic devices, andfor the resulting printed LED-based devices and photovoltaic devices.

SUMMARY

The exemplary embodiments provide a “diode ink”, namely, a liquid or gelsuspension and dispersion of diodes or other two-terminal integratedcircuits which is capable of being printed, such as through screenprinting or flexographic printing, for example. As described in greaterdetail below, the diodes themselves, prior to inclusion in the diode inkcomposition, are fully formed semiconductor devices which are capable offunctioning when energized to emit light (when embodied as LEDs) orprovide power when exposed to a light source (when embodied asphotovoltaic diodes). An exemplary method also comprises a method ofmanufacturing diode ink which, as discussed in greater detail below,disperses and suspends a plurality of diodes in a solvent and viscousresin or polymer mixture which is capable of being printed tomanufacture LED-based devices and photovoltaic devices. Exemplaryapparatuses and systems formed by printing such a diode ink are alsodisclosed.

While the description is focused on diodes as a type of two-terminalintegrated circuit, those having skill in the art will recognize thatother types of semiconductor devices may be substituted equivalently toform what is referred to more broadly as a “semiconductor device ink”,and that all such variations are considered equivalent and within thescope of the disclosure. Accordingly, any reference herein to “diode”shall be understood to mean and include any two-terminal integratedcircuit, of any kind, such as resistors, inductors, capacitors, RFIDcircuits, sensors, piezo-electric devices, etc., and any otherintegrated circuit which may be operated using two terminals orelectrodes.

An exemplary embodiment provides a composition comprising: a pluralityof diodes; a first solvent; and a viscosity modifier.

In an exemplary embodiment, the first solvent comprises at least onesolvent selected from the group consisting of: water; alcohols such asmethanol, ethanol, N-propanol (including 1-propanol, 2-propanol(isopropanol), 1-methoxy-2-propanol), butanol (including 1-butanol,2-butanol (isobutanol), pentanol (including 1-pentanol, 2-pentanol,3-pentanol), octanol, N-octanol (including 1-octanol, 2-octanol,3-octanol), tetrahydrofurfuryl alcohol, cyclohexanol, terpineol; etherssuch as methyl ethyl ether, diethyl ether, ethyl propyl ether, andpolyethers; esters such ethyl acetate, dimethyl adipate, propyleneglycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate,glycerin acetate; glycols such as ethylene glycols, diethylene glycol,polyethylene glycols, propylene glycols, dipropylene glycols, glycolethers, glycol ether acetates; carbonates such as propylene carbonate;glycerols such as glycerin; acetonitrile, tetrahydrofuran (THF),dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide(DMSO); acids such as acetic acid, nitric acid, sulfuric acid; basessuch as ammonium hydroxide, sodium hydroxide, potassium hydroxide; andmixtures thereof. The first solvent may be present in an amount of about0.3% to 50% or 60% by weight, for example.

In various exemplary embodiments, each diode of the plurality of diodeshas a diameter between about 20 to 30 microns and a height between about5 to 15 microns; or has a diameter between about 10 to 50 microns and aheight between about 5 to 25 microns; or has a width and length eachbetween about 10 to 50 microns and a height between about 5 to 25microns; or has a width and length each between about 20 to 30 micronsand a height between about 5 to 15 microns. The plurality of diodes maybe light emitting diodes or photovoltaic diodes, for example.

An exemplary composition may further comprise a plurality ofsubstantially optically transparent and chemically inert particleshaving a range of sizes between about 10 to about 50 microns and presentin an amount of about 0.1% to 2.5% by weight. Another exemplarycomposition may further comprise a plurality of substantially opticallytransparent and chemically inert particles having a range of sizesbetween about 10 to about 30 microns and present in an amount of about0.1% to 2.5% by weight.

In an exemplary embodiment, the viscosity modifier comprises at leastone viscosity modifier selected from the group consisting of: clays suchas hectorite clays, garamite clays, organo-modified clays; saccharidesand polysaccharides such as guar gum, xanthan gum; celluloses andmodified celluloses such as hydroxy methylcellulose, methylcellulose,ethyl cellulose, propyl methylcellulose, methoxy cellulose, methoxymethylcellulose, methoxy propyl methylcellulose, hydroxy propylmethylcellulose, carboxy methylcellulose, hydroxy ethylcellulose, ethylhydroxyl ethylcellulose, cellulose ether, cellulose ethyl ether,chitosan; polymers such as acrylate and (meth)acrylate polymers andcopolymers; glycols such as ethylene glycols, diethylene glycol,polyethylene glycols, propylene glycols, dipropylene glycols, glycolethers, glycol ether acetates; fumed silica, silica powders; modifiedureas; and mixtures thereof. The viscosity modifier may be present in anamount of about 0.30% to 5% by weight, or about 0.10% to 3% by weight,for example.

The composition may further comprise a second solvent different from thefirst solvent. The second solvent is present in an amount of about 0.1%to 60% by weight, for example.

In an exemplary embodiment, the first solvent comprises N-propanol,isopropanol, dipropylene glycol, diethylene glycol, propylene glycol,1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, orcyclohexanol, or mixtures thereof, and present in an amount of about 5%to 50% by weight; the viscosity modifier comprises methoxy propylmethylcellulose resin or hydroxy propyl methylcellulose resin ormixtures thereof, and present in an amount of about 0.10% to 5.0% byweight; and the second solvent comprises N-propanol, isopropanol,dipropylene glycol, diethylene glycol, propylene glycol,1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, orcyclohexanol, or mixtures thereof, and present in an amount of about0.3% to 50% by weight.

In another exemplary embodiment, the first solvent comprises N-propanol,isopropanol, dipropylene glycol, diethylene glycol, propylene glycol,1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, orcyclohexanol, or mixtures thereof, and present in an amount of about 5%to 30% by weight; the viscosity modifier comprises methoxy propylmethylcellulose resin or hydroxy propyl methylcellulose resin ormixtures thereof, and present in an amount of about 1.0% to 3.0% byweight; and the second solvent comprises N-propanol, isopropanol,dipropylene glycol, diethylene glycol, propylene glycol,1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, orcyclohexanol, or mixtures thereof, and present in an amount of about0.2% to 8.0% by weight; and wherein the balance of the compositionfurther comprises water.

In another exemplary embodiment, the first solvent comprises N-propanol,isopropanol, dipropylene glycol, diethylene glycol, propylene glycol,1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, orcyclohexanol, or mixtures thereof, and present in an amount of about 40%to 60% by weight; the viscosity modifier comprises methoxy propylmethylcellulose resin or hydroxy propyl methylcellulose resin ormixtures thereof, and present in an amount of about 0.10% to 1.5% byweight; and the second solvent comprises N-propanol, isopropanol,dipropylene glycol, diethylene glycol, propylene glycol,1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol, orcyclohexanol, or mixtures thereof, and present in an amount of about 40%to 60% by weight.

An exemplary method of making the composition may comprise: mixing theplurality of diodes with the first solvent; adding the mixture of thefirst solvent and plurality of diodes to the viscosity modifier; addingthe second solvent; and mixing the plurality of diodes, the firstsolvent, the second solvent, and the viscosity modifier for about 25 to30 minutes in an air atmosphere. An exemplary method may furthercomprise releasing the plurality of diodes from a wafer, and the step ofreleasing the plurality of diodes from the wafer further comprisesetching the back side of the wafer, grinding and polishing a back sideof the wafer, or a laser lift-off from a back side of the wafer, forexample.

In various exemplary embodiments, the composition has a viscositysubstantially between about 50 cps and about 25,000 cps at about 25° C.,or between about 100 cps and about 25,000 cps at about 25° C., orbetween about 1,000 cps and about 10,000 cps at about 25° C., or betweenabout 10,000 cps and about 25,000 cps at about 25° C.

In various exemplary embodiments, each diode of the plurality of diodesmay comprise GaN and wherein the GaN portion of each diode of theplurality of diodes is substantially hexagonal, square, triangular,rectangular, lobed, stellate, or toroidal. In an exemplary embodiment, alight emitting or absorbing region of each diode of the plurality ofdiodes may have a surface texture selected from the group consisting of:a plurality of circular rings, a plurality of substantially curvilineartrapezoids, a plurality of parallel stripes, a stellate pattern, andmixtures thereof.

In an exemplary embodiment, each diode of the plurality of diodes has afirst metal terminal on a first side of the diode and a second metalterminal on a second, back side of the diode, and the first and secondterminals are each between about 1 to 6 microns in height. In anotherexemplary embodiment, each diode of the plurality of diodes has adiameter between about 20 to 30 microns and a height between 5 to 15microns, and each diode of the plurality of diodes has a plurality offirst metal terminals on a first side and one second metal terminal onthe first side, a contact of the second metal terminal spaced apart fromcontacts of the plurality of first metal terminals by about 2 to 5microns in the height dimension. In an exemplary embodiment, each firstmetal terminal of the plurality of first metal terminals is betweenabout 0.5 to 2 microns in height and the second metal terminal isbetween about 1 to 8 microns in height. In another exemplary embodiment,each diode of the plurality of diodes has a diameter between about 10 to50 microns and a height between 5 to 25 microns, and each diode of theplurality of diodes has a plurality of first metal terminals on a firstside and one second metal terminal on the first side, a contact of thesecond metal terminal spaced apart from contacts of the plurality offirst metal terminals by about 1 to 7 microns in the height dimension.

In another exemplary embodiment, each diode of the plurality of diodeshas at least one metal via structure extending between at least one p+or n+ GaN layer on a first side of the diode to a second, back side ofthe diode. The metal via structure comprises a central via, a peripheralvia, or a perimeter via, for example.

In various exemplary embodiments, each diode of the plurality of diodesis less than about 30 microns in any dimension. In another exemplaryembodiment, the diode has a diameter between about 20 to 30 microns anda height between about 5 to 15 microns; or a diameter between about 10to 50 microns and a height between about 5 to 25 microns; or issubstantially hexagonal laterally, has a diameter between about 10 to 50microns measured opposing face-to face, and a height between about 5 to25 microns; or is substantially hexagonal laterally, has a diametermeasured opposing face-to face between about 20 to 30 microns and aheight between about 5 to 15 microns; or has a width and length eachbetween about 10 to 50 microns each and a height between about 5 to 25microns; or has a width and length each between about 20 to 30 micronseach and a height between about 5 to 15 microns. In various exemplaryembodiments, the lateral sides of each diode of the plurality of diodesare less than about 10 microns in height. In another exemplaryembodiment, the lateral sides of each diode of the plurality of diodesare between about 2.5 to 6 microns in height. In another exemplaryembodiment, the lateral sides of each diode of the plurality of diodesare substantially sigmoidal and terminate in a curved point.

In various exemplary embodiments, the viscosity modifier furthercomprises an adhesive viscosity modifier. The viscosity modifier, whendried or cured, may form a polymer or resin lattice or structuresubstantially about the periphery of each diode of the plurality ofdiodes. The composition may be visually opaque when wet andsubstantially optically clear when dried or cured, for example. Thecomposition may have a contact angle greater than about 25 degrees orgreater than about 40 degrees. The composition may have a relativeevaporation rate less than one, wherein the evaporation rate is relativeto butyl acetate having a rate of one. A method of using the compositionmay comprise printing the composition over a base or over a firstconductor coupled to the base.

In an exemplary embodiment, each diode of the plurality of diodescomprises at least one inorganic semiconductor selected from the groupconsisting of: silicon, gallium arsenide (GaAs), gallium nitride (GaN),GaP, InAlGaP, InAlGaP, AlInGaAs, InGaNAs, and AlInGASb. In anotherexemplary embodiment, each diode of the plurality of diodes comprises atleast one organic semiconductor selected from the group consisting of:π-conjugated polymers, poly(acetylene)s, poly(pyrrole)s,poly(thiophene)s, polyanilines, polythiophenes, poly(p-phenylenesulfide), poly(para-phenylene vinylene)s (PPV) and PPV derivatives,poly(3-alkylthiophenes), polyindole, polypyrene, polycarbazole,polyazulene, polyazepine, poly(fluorene)s, polynaphthalene, polyaniline,polyaniline derivatives, polythiophene, polythiophene derivatives,polypyrrole, polypyrrole derivatives, polythianaphthene,polythianaphthane derivatives, polyparaphenylene, polyparaphenylenederivatives, polyacetylene, polyacetylene derivatives, polydiacethylene,polydiacetylene derivatives, polyparaphenylenevinylene,polyparaphenylenevinylene derivatives, polynaphthalene, polynaphthalenederivatives, polyisothianaphthene (PITN), polyheteroarylenvinylene(ParV) in which the heteroarylene group is thiophene, furan or pyrrol,polyphenylene-sulphide (PPS), polyperinaphthalene (PPN),polyphthalocyanine (PPhc), and their derivatives, copolymers thereof andmixtures thereof.

Another exemplary embodiment provides a composition comprising: aplurality of diodes; a first solvent; and a viscosity modifier; whereinthe composition has a viscosity substantially about 100 cps to about25,000 cps at about 25° C. Another exemplary embodiment provides acomposition comprising: a plurality of diodes, each diode of theplurality of diodes less than about 50 microns in any dimension; a firstsolvent; a second solvent different from the first solvent; and aviscosity modifier; wherein the composition has a viscositysubstantially about 50 cps to about 25,000 cps at about 25° C. Anotherexemplary embodiment provides a composition comprising: a plurality ofdiodes less than about 50 microns in any dimension; and a viscositymodifier to provide a viscosity of the composition substantially betweenabout 100 cps and about 20,000 cps at about 25° C. Another exemplaryembodiment provides a composition comprising: a plurality of diodes; afirst solvent selected from the group consisting of: N-propanol,isopropanol, dipropylene glycol, diethylene glycol, propylene glycol,1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl alcohol,cyclohexanol, and mixtures thereof; a viscosity modifier selected fromthe group consisting of: methoxy propyl methylcellulose resin, hydroxypropyl methylcellulose resin, and mixtures thereof; and a second solventdifferent from the first solvent, the second solvent selected from thegroup consisting of: N-propanol, isopropanol, dipropylene glycol,diethylene glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol,ethanol, tetrahydrofurfuryl alcohol, cyclohexanol, and mixtures thereof.

Another exemplary embodiment provides an apparatus comprising: aplurality of diodes; at least a trace amount of a first solvent; and apolymeric or resin film at least partially surrounding each diode of theplurality of diodes. In an exemplary embodiment, the polymeric or resinfilm comprises a methylcellulose resin having a thickness between about10 nm to 300 nm. In another exemplary embodiment, the polymeric or resinfilm comprises a methoxy propyl methylcellulose resin or a hydroxypropyl methylcellulose resin or mixtures thereof. The apparatus mayfurther comprise at least a trace amount of a second solvent differentfrom the first solvent.

In an exemplary embodiment, the polymeric or resin film comprises acured, dried or polymerized viscosity modifier selected from the groupconsisting of: clays such as hectorite clays, garamite clays,organo-modified clays; saccharides and polysaccharides such as guar gum,xanthan gum; celluloses and modified celluloses such as hydroxymethylcellulose, methylcellulose, ethyl cellulose, propylmethylcellulose, methoxy cellulose, methoxy methylcellulose, methoxypropyl methylcellulose, hydroxy propyl methylcellulose, carboxymethylcellulose, hydroxy ethylcellulose, ethyl hydroxyl ethylcellulose,cellulose ether, cellulose ethyl ether, chitosan; polymers such asacrylate and (meth)acrylate polymers and copolymers; glycols such asethylene glycols, diethylene glycol, polyethylene glycols, propyleneglycols, dipropylene glycols, glycol ethers, glycol ether acetates;fumed silica, silica powders; modified ureas; and mixtures thereof.

An exemplary apparatus may further comprise a plurality of substantiallyoptically transparent and chemically inert particles, each inertparticle of the plurality of substantially optically transparent andchemically inert particles between about 10 to about 50 microns; whereinthe polymeric or resin film further at least partially surrounds eachinert particle of the plurality of substantially optically transparentand chemically inert particles.

An exemplary apparatus may further comprise: a base; one or more firstconductors coupled to the first terminals; at least one dielectric layercoupled to the one or more first conductors; and one or more secondconductors coupled to the second terminals and to the dielectric layer.In an exemplary embodiment, at least one diode of the plurality ofdiodes has a first terminal coupled to at least one second conductor anda second terminal coupled to at least one first conductor. In anotherexemplary embodiment, a first portion of the plurality of diodes havefirst terminals coupled to at least one first conductor and secondterminals coupled to at least one second conductor, and wherein a secondportion of the plurality of diodes have first terminals coupled to atleast one second conductor and second terminals coupled to at least onefirst conductor. An exemplary apparatus may further comprise: aninterface circuit coupled to the one or more first conductors and to theone or more second conductors, the interface circuit further couplableto a power source.

In various exemplary embodiments, the one or more first conductors mayfurther comprise: a first electrode comprising a first busbar and afirst plurality of elongated conductors extending from the first busbar;and a second electrode comprising a second busbar and a second pluralityof elongated conductors extending from the second busbar. The secondplurality of elongated conductors may be interdigitated with the firstplurality of elongated conductors. The one or more second conductors maybe further coupled to the second plurality of elongated conductors.

In various exemplary embodiments, the apparatus is foldable andbendable. The apparatus may be substantially flat and have a totalthickness less than about 3 mm. The apparatus may be die cut and foldedinto a selected shape. The apparatus may have an average surface areaconcentration of the plurality of diodes from about 25 to 50,000 diodesper square centimeter. In various exemplary embodiments, the apparatusdoes not include a heat sink or a heat sink component.

In another exemplary embodiment, an apparatus comprises: a base; aplurality of diodes, each diode of the plurality of diodes having afirst terminal and a second terminal, each diode of the plurality ofdiodes less than about 50 microns in any dimension; a film substantiallysurrounding each diode of the plurality of diodes, the film comprising apolymer or a resin and having a thickness between about 10 nm to 300 nm;one or more first conductors coupled to a first plurality of firstterminals; a first dielectric layer coupled to the one or more firstconductors; and one or more second conductors coupled to a firstplurality of second terminals.

In another exemplary embodiment, an apparatus comprises: a base; one ormore first conductors; a dielectric layer coupled to the one or morefirst conductors; one or more second conductors; a plurality of diodes,each diode of the plurality of diodes less than about 50 microns in anydimension, a first portion of the plurality of diodes coupled to the oneor more first conductors and to the one or more second conductors in aforward bias orientation, and at least one diode of the plurality ofdiodes coupled to the one or more first conductors and to the one ormore second conductors in a reverse bias orientation; and a filmsubstantially surrounding each diode of the plurality of diodes, thefilm comprising a polymer or a resin and having a thickness betweenabout 10 nm to 300 nm;

In various exemplary embodiments, a diode comprises: a light emitting orabsorbing region having a diameter between about 20 and 30 microns and aheight between about 2.5 to 7 microns; a first terminal coupled to thelight emitting region on a first side, the first terminal having aheight between about 1 to 6 microns; and a second terminal coupled tothe light emitting region on a second side opposite the first side, thesecond terminal having a height between about 1 to 6 microns.

In another exemplary embodiment, a diode comprises: a light emitting orabsorbing region having a diameter between about 6 and 30 microns and aheight between about 1 to 7 microns; a first terminal coupled to thelight emitting region on a first side, the first terminal having aheight between about 1 to 6 microns; and a second terminal coupled tothe light emitting region on a second side opposite the first side, thesecond terminal having a height between about 1 to 6 microns; whereinthe diode is substantially hexagonal laterally, has a diameter betweenabout 10 to 50 microns measured opposing face-to-face and a heightbetween about 5 to 25 microns, and wherein each lateral side of thediode is less than about 10 microns in height, has a substantiallysigmoidal curvature and terminates in a curved point.

In another exemplary embodiment, a diode comprises: a light emitting orabsorbing region having a diameter between about 6 and 30 microns and aheight between about 1 to 7 microns; a first terminal coupled to thelight emitting region on a first side, the first terminal having aheight between about 1 to 6 microns; and a second terminal coupled tothe light emitting region on a second side opposite the first side, thesecond terminal having a height between about 1 to 6 microns; whereinthe diode has a width and a length each between about 10 to 50 micronsand a height between about 5 to 25 microns, and wherein each lateralside of the diode is less than about 10 microns in height, has asubstantially sigmoidal curvature and terminates in a curvilinear point.

In various exemplary embodiments, a diode comprises: a light emitting orabsorbing region having a diameter between about 6 and 30 microns and aheight between about 2.5 to 7 microns; a first terminal coupled to thelight emitting region on a first side, the first terminal having aheight between about 3 to 6 microns; and a second terminal coupled tothe light emitting region on a second side opposite the first side, thesecond terminal having a height between about 3 to 6 microns; whereinthe diode has a width and a length each between about 10 to 30 micronsand a height between about 5 to 15 microns, and wherein each lateralside of the diode is less than about 10 microns in height, has asubstantially sigmoidal curvature and terminates in a curvilinear point.

In another exemplary embodiment, a diode comprises: a light emitting orabsorbing region having a diameter between about 20 and 30 microns and aheight between 2.5 to 7 microns; a plurality of first terminals spacedapart and coupled to the light emitting region peripherally on a firstside, each first terminal of the plurality of first terminals having aheight between about 0.5 to 2 microns; and one second terminal coupledcentrally to a mesa region of the light emitting region on the firstside, the second terminal having a height between 1 to 8 microns.

In another exemplary embodiment, a diode comprises: a light emitting orabsorbing region having a mesa region, the mesa region having a heightof 0.5 to 2 microns and a diameter between about 6 to 22 microns; aplurality of first terminals spaced apart and coupled to the lightemitting region on a first side and peripherally to the mesa region,each first terminal of the plurality of first terminals having a heightbetween about 0.5 to 2 microns; and one second terminal coupledcentrally to the mesa region of the light emitting region on the firstside, the second terminal having a height between 1 to 8 microns;wherein the diode has a lateral dimension between about 10 to 50 micronsand a height between about 5 to 25 microns.

In another exemplary embodiment, a diode comprises: a light emitting orabsorbing region having a diameter between about 20 and 30 microns and aheight between 2.5 to 7 microns; a plurality of first terminals spacedapart and coupled to the light emitting region peripherally on a firstside, each first terminal having a height between about 0.5 to 2microns; and one second terminal coupled centrally to a mesa region ofthe light emitting region on the first side, the second terminal havinga height between 3 to 6 microns; wherein the diode is substantiallyhexagonal laterally, has a diameter between about 20 to 30 microns and aheight between about 5 to 15 microns, wherein each lateral side of thediode is less than about 10 microns in height, has a substantiallysigmoidal curvature and terminates in a curved point.

In another exemplary embodiment, a diode comprises: a light emitting orabsorbing region having a mesa region, the mesa region having a heightof 0.5 to 2 microns and a diameter between about 6 to 22 microns; aplurality of first terminals spaced apart and coupled to the lightemitting region on a first side and peripherally to the mesa region,each first terminal of the plurality of first terminals having a heightbetween about 0.5 to 2 microns; and one second terminal coupledcentrally to the mesa region of the light emitting region on the firstside, the second terminal having a height between 1 to 8 microns, thesecond metal terminal having one contact, and the one contact of thesecond terminal spaced apart from contacts of the plurality of firstmetal terminals by about 1 to 7 microns in height; wherein the diode issubstantially hexagonal laterally, has a diameter between about 10 to 50microns and a height between about 5 to 25 microns, wherein each lateralside of the diode is less than about 15 microns in height, has asubstantially sigmoidal curvature and terminates in a curved point.

An exemplary method of making a liquid or gel suspension of diodes forprinting, comprises: adding a viscosity modifier to a plurality ofdiodes in a first solvent; and mixing the plurality of diodes, the firstsolvent and the viscosity modifier to form the liquid or gel suspensionof the plurality of diodes.

In another exemplary embodiment, a method of making a liquid or gelsuspension of diodes for printing comprises: adding a second solvent toa plurality of diodes in a first solvent, the second solvent differentfrom the first solvent; adding a viscosity modifier to the plurality ofdiodes, the first solvent and the second solvent; adding a plurality ofsubstantially chemically inert particles to the plurality of diodes, thefirst solvent, the second solvent and the viscosity modifier; and mixingthe plurality of diodes, the first solvent, the second solvent, theviscosity modifier, and the plurality of substantially chemically inertparticles until the viscosity is at least about 100 centipoise (cps)measured at about 25° C. to form the liquid or gel suspension of theplurality of diodes.

In another exemplary embodiment, a method of making a liquid or gelsuspension of diodes for printing comprises: adding a viscosity modifierto a plurality of diodes, a first solvent and a second solvent, thesecond solvent different from the first solvent, wherein each diode ofthe plurality of diodes has a lateral dimension between about 10 to 50microns and a height between about 5 to 25 microns; adding a pluralityof substantially chemically inert particles to the plurality of diodes,the first solvent, the second solvent and the viscosity modifier,wherein each particle of the plurality of substantially chemically inertparticles has a size between about 10 microns to about 70 microns in anydimension; and mixing the plurality of diodes, the first solvent, thesecond solvent, the viscosity modifier, and the plurality ofsubstantially chemically inert particles until the viscosity is at leastabout 1,000 centipoise (cps) measured at about 25° C. to form the liquidor gel suspension of the plurality of diodes.

In an exemplary embodiment, a method of fabricating an electronic devicecomprises: depositing one or more first conductors; and depositing aplurality of diodes suspended in a mixture of a first solvent and aviscosity modifier.

In another exemplary embodiment, a method comprises: depositing aplurality of diodes suspended in a mixture of first solvent and aviscosity modifier on a first side of an optically transmissive base,each diode of the plurality of diodes having a plurality of firstterminals on a first side and one second terminal on the first side,each diode of the plurality of diodes having a lateral dimension betweenabout 10 to 50 microns and a height between 5 to 25 microns; depositingone or more first conductors coupled to the first terminals; depositingat least one dielectric layer coupled to the one or more firstconductors; depositing one or more second conductors coupled to thesecond terminals; and depositing a first phosphor layer on a second sideof the optically transmissive base.

In another exemplary embodiment, a method comprises: depositing one ormore first conductors on a first side of a base; depositing a pluralityof diodes suspended in a mixture of a first solvent and a viscositymodifier over the one or more first conductors, each diode of theplurality of diodes having a first terminal on a first side and a secondterminal on a second side, each diode of the plurality of diodes havinga lateral dimension between about 10 to 50 microns and a height between5 to 25 microns; depositing at least one dielectric layer over theplurality of diodes and the one or more first conductors; depositing oneor more optically transmissive second conductors over the dielectriclayer; and depositing a first phosphor layer.

In another exemplary embodiment, a composition comprises: a plurality oftwo-terminal integrated circuits, each two-terminal integrated circuitof the plurality of two-terminal integrated circuits less than about 75microns in any dimension; a first solvent; a second solvent differentfrom the first solvent; and a viscosity modifier; wherein thecomposition has a viscosity substantially about 50 cps to about 25,000cps at about 25° C. In various exemplary embodiments, the plurality oftwo-terminal integrated circuits comprise a two-terminal integratedcircuit selected from the group consisting of: diodes, light emittingdiodes, photovoltaic diodes, resistors, inductors, capacitors, RFIDintegrated circuits, sensor integrated circuits, and piezo-electricintegrated circuits.

In another exemplary embodiment, an apparatus comprises: a base; aplurality of two-terminal integrated circuits, each two-terminalintegrated circuit of the plurality of two-terminal integrated circuitsless than about 75 microns in any dimension; at least a trace amount ofa first solvent; a film substantially surrounding each diode of theplurality of diodes, the film comprising a methylcellulose resin andhaving a thickness between about 10 nm to 300 nm; one or more firstconductors coupled to the plurality of two-terminal integrated circuits;a first dielectric layer coupled to the one or more first conductors;and one or more second conductors coupled to the plurality oftwo-terminal integrated circuits.

In another exemplary embodiment, a composition comprises: a plurality oftwo-terminal integrated circuits, each two-terminal integrated circuitof the plurality of two-terminal integrated circuits less than about 75microns in any dimension; a first solvent; a second solvent differentfrom the first solvent; a plurality of substantially chemically inertparticles having a range of sizes between about 10 to about 100 micronsand present in an amount of about 0.1% to 2.5% by weight; and aviscosity modifier; wherein the composition has a viscositysubstantially about 50 cps to about 25,000 cps at about 25° C.

Numerous other advantages and features of the present invention willbecome readily apparent from the following detailed description of theinvention and the embodiments thereof, from the claims and from theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects, features and advantages of the present invention will bemore readily appreciated upon reference to the following disclosure whenconsidered in conjunction with the accompanying drawings, wherein likereference numerals are used to identify identical components in thevarious views, and wherein reference numerals with alphabetic charactersare utilized to identify additional types, instantiations or variationsof a selected component embodiment in the various views, in which:

FIG. 1 is a perspective view illustrating an exemplary first diodeembodiment.

FIG. 2 is a plan (or top) view illustrating the exemplary first diodeembodiment.

FIG. 3 is a cross-sectional view illustrating the exemplary first diodeembodiment.

FIG. 4 is a perspective view illustrating an exemplary second diodeembodiment.

FIG. 5 is a plan (or top) view illustrating the exemplary second diodeembodiment.

FIG. 6 is a perspective view illustrating an exemplary third diodeembodiment.

FIG. 7 is a plan (or top) view illustrating the exemplary third diodeembodiment.

FIG. 8 is a perspective view illustrating an exemplary fourth diodeembodiment.

FIG. 9 is a plan (or top) view illustrating the exemplary fourth diodeembodiment.

FIG. 10 is a cross-sectional view illustrating an exemplary second,third and/or fourth diode embodiment.

FIG. 11 is a perspective view illustrating exemplary fifth and sixthdiode embodiments.

FIG. 12 is a plan (or top) view illustrating the exemplary fifth andsixth diode embodiments.

FIG. 13 is a cross-sectional view illustrating the exemplary fifth diodeembodiment.

FIG. 14 is a cross-sectional view illustrating the exemplary sixth diodeembodiment.

FIG. 15 is a perspective view illustrating an exemplary seventh diodeembodiment.

FIG. 16 is a plan (or top) view illustrating the exemplary seventh diodeembodiment.

FIG. 17 is a cross-sectional view illustrating the exemplary seventhdiode embodiment.

FIG. 18 is a perspective view illustrating an exemplary eighth diodeembodiment.

FIG. 19 is a plan (or top) view illustrating the exemplary eighth diodeembodiment.

FIG. 20 is a cross-sectional view illustrating the exemplary eighthdiode embodiment.

FIG. 21 is a perspective view illustrating an exemplary tenth diodeembodiment.

FIG. 22 is a cross-sectional view illustrating the exemplary tenth diodeembodiment.

FIG. 23 is a perspective view illustrating an exemplary eleventh diodeembodiment.

FIG. 24 is a cross-sectional view illustrating the exemplary eleventhdiode embodiment.

FIG. 25 is a cross-sectional view illustrating a portion of a complexGaN heterostructure and metal layers illustrating optional geometriesand textures of the external and/or internal surfaces of the complex GaNheterostructure.

FIG. 26 is a cross-sectional view of a wafer having an oxide layer, suchas silicon dioxide.

FIG. 27 is a cross-sectional view of a wafer having an oxide layeretched in a grid pattern.

FIG. 28 is a plan (or top) view of a wafer having an oxide layer etchedin a grid pattern.

FIG. 29 is a cross-sectional view of a wafer having a buffer layer (suchas aluminum nitride or silicon nitride), a silicon dioxide layer in agrid pattern, and gallium nitride (GaN) layers.

FIG. 30 is a cross-sectional view of a substrate having a buffer layerand a complex GaN heterostructure (n+ GaN layer, quantum well region,and p+ GaN layer).

FIG. 31 is a cross-sectional view of a substrate having a buffer layerand a first mesa-etched complex GaN heterostructure.

FIG. 32 is a cross-sectional view of a substrate having a buffer layerand a second mesa-etched complex GaN heterostructure.

FIG. 33 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, and etched substrate for viaconnections.

FIG. 34 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, and metallization forming vias.

FIG. 35 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming vias, andlateral etched trenches.

FIG. 36 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming vias, lateraletched trenches, and passivation layers (such as silicon nitride).

FIG. 37 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming vias, lateraletched trenches, passivation layers, and metallization forming aprotruding or bump structure.

FIG. 38 is a cross-sectional view of a substrate having a complex GaNheterostructure (n+ GaN layer, quantum well region, and p+ GaN layer).

FIG. 39 is a cross-sectional view of a substrate having a thirdmesa-etched complex GaN heterostructure.

FIG. 40 is a cross-sectional view of a substrate having a mesa-etchedcomplex GaN heterostructure, an etched substrate for via connections,and lateral etched trenches.

FIG. 41 is a cross-sectional view of a substrate having a mesa-etchedcomplex GaN heterostructure, metallization forming an ohmic contact withthe n+ GaN layer and forming through vias, and lateral etched trenches.

FIG. 42 is a cross-sectional view of a substrate having a mesa-etchedcomplex GaN heterostructure, metallization forming an ohmic contact withthe n+ GaN layer and forming through vias, metallization forming anohmic contact with the p+ GaN layer, and lateral etched trenches.

FIG. 43 is a cross-sectional view of a substrate having a mesa-etchedcomplex GaN heterostructure, metallization forming an ohmic contact withthe n+ GaN layer and forming through vias, metallization forming anohmic contact with the p+ GaN layer, lateral etched trenches, andpassivation layers (such as silicon nitride).

FIG. 44 is a cross-sectional view of a substrate having a mesa-etchedcomplex GaN heterostructure, metallization forming an ohmic contact withthe n+ GaN layer and forming through vias, metallization forming anohmic contact with the p+ GaN layer, lateral etched trenches,passivation layers (such as silicon nitride), and metallization forminga protruding or bump structure.

FIG. 45 is a cross-sectional view of a substrate having a buffer layer,a complex GaN heterostructure (n+ GaN layer, quantum well region, andp+GaN layer), and metallization forming an ohmic contact with the p+ GaNlayer.

FIG. 46 is a cross-sectional view of a substrate having a buffer layer,a fourth mesa-etched complex GaN heterostructure, and metallizationforming an ohmic contact with the p+ GaN layer.

FIG. 47 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, and metallization forming an ohmiccontact with the n+ GaN layer.

FIG. 48 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the n+ GaN layer, and lateral etched trenches.

FIG. 49 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming an ohmiccontact with the n+ GaN layer, and lateral etched trenches havingmetallization forming through, perimeter vias.

FIG. 50 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming an ohmiccontact with the n+ GaN layer, and lateral etched trenches havingmetallization forming through, perimeter vias, passivation layers (suchas silicon nitride), and metallization forming a protruding or bumpstructure.

FIG. 51 is a cross-sectional view of a substrate having a buffer layer,a fifth mesa-etched complex GaN heterostructure, and metallizationforming an ohmic contact with the p+ GaN layer.

FIG. 52 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, and etched GaN heterostructure fora center via connection.

FIG. 53 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, and metallization forming a centervia and an ohmic contact with the n+ GaN layer.

FIG. 54 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming a center viaand an ohmic contact with the n+ GaN layer, and a first passivationlayer (such as silicon nitride).

FIG. 55 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming a center viaand an ohmic contact with the n+ GaN layer, a first passivation layer(such as silicon nitride), and metallization forming a protruding orbump structure.

FIG. 56 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming a center viaand an ohmic contact with the n+ GaN layer, a first passivation layer(such as silicon nitride), metallization forming a protruding or bumpstructure, and lateral (or perimeter) etched trenches.

FIG. 57 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming a center viaand an ohmic contact with the n+ GaN layer, a first passivation layer(such as silicon nitride), metallization forming a protruding or bumpstructure, lateral (or perimeter) etched trenches, and a secondpassivation layer (such as silicon nitride).

FIG. 58 is a cross-sectional view of a substrate having a buffer layer,a sixth mesa-etched complex GaN heterostructure, and metallizationforming an ohmic contact with the p+ GaN layer.

FIG. 59 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, and metallization forming an ohmiccontact with the n+ GaN layer.

FIG. 60 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming an ohmiccontact with the n+GaN layer, and additional metallization for contactwith the p+ GaN layer.

FIG. 61 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming an ohmiccontact with the n+ GaN layer, additional metallization for contact withthe p+ GaN layer, and metallization forming a protruding or bumpstructure.

FIG. 62 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming an ohmiccontact with the n+ GaN layer, additional metallization for contact withthe p+ GaN layer, metallization forming a protruding or bump structure,and passivation layers (such as silicon nitride).

FIG. 63 is a cross-sectional view of a substrate having a buffer layer,a mesa-etched complex GaN heterostructure, metallization forming anohmic contact with the p+ GaN layer, metallization forming an ohmiccontact with the n+ GaN layer, additional metallization for contact withthe p+ GaN layer, metallization forming a protruding or bump structure,passivation layers (such as silicon nitride), and lateral (or perimeter)etched trenches.

FIG. 64 is a cross-sectional view illustrating an exemplary diode waferembodiment adhered to a holding apparatus.

FIG. 65 is a cross-sectional view illustrating an exemplary diode waferembodiment adhered to a holding apparatus.

FIG. 66 is a cross-sectional view illustrating an exemplary tenth diodeembodiment adhered to a holding apparatus.

FIG. 67 is a cross-sectional view illustrating an exemplary tenth diodeembodiment prior to back side metallization adhered to a holdingapparatus.

FIG. 68 is a cross-sectional view illustrating an exemplary diodeembodiment adhered to a holding apparatus.

FIG. 69 is a cross-sectional view illustrating an exemplary eleventhdiode embodiment adhered to a holding apparatus.

FIG. 70 is a flow diagram illustrating an exemplary first methodembodiment for diode fabrication.

FIG. 71, divided into FIG. 71A and FIG. 71B, is a flow diagramillustrating an exemplary second method embodiment for diodefabrication.

FIG. 72, divided into FIG. 72A and FIG. 72B, is a flow diagramillustrating an exemplary third method embodiment for diode fabrication.

FIG. 73, divided into FIG. 73A and FIG. 73B, is a flow diagramillustrating an exemplary fourth method embodiment for diodefabrication.

FIG. 74 is a cross-sectional view illustrating an exemplary ground andpolished diode wafer embodiment adhered to a holding apparatus andsuspended in a dish with adhesive solvent.

FIG. 75 is a flow diagram illustrating an exemplary method embodimentfor diode suspension fabrication.

FIG. 76 is a perspective view of an exemplary first apparatusembodiment.

FIG. 77 is a plan (or top) view illustrating an exemplary firstelectrode structure of a first conductive layer for an exemplaryapparatus embodiment.

FIG. 78 is a first cross-sectional view of an exemplary first apparatusembodiment.

FIG. 79 is a second cross-sectional view of an exemplary first apparatusembodiment.

FIG. 80 is a perspective view of an exemplary second apparatusembodiment.

FIG. 81 is a first cross-sectional view of an exemplary second apparatusembodiment.

FIG. 82 is a second cross-sectional view of an exemplary secondapparatus embodiment.

FIG. 83 is a second cross-sectional view of exemplary diodes coupled toa first conductor.

FIG. 84 is a block diagram of a first exemplary system embodiment.

FIG. 85 is a block diagram of a second exemplary system embodiment.

FIG. 86 is a flow diagram illustrating an exemplary method embodimentfor apparatus fabrication.

FIG. 87 is a cross-sectional view of an exemplary third apparatusembodiment to provide light emission from two sides.

FIG. 88 is a cross-sectional view of an exemplary fourth apparatusembodiment to provide light emission from two sides.

FIG. 89 is a partial cross-sectional view in greater detail of anexemplary first apparatus embodiment.

FIG. 90 is a partial cross-sectional view in greater detail of anexemplary second apparatus embodiment.

FIG. 91 is a perspective view of an exemplary fifth apparatusembodiment.

FIG. 92 is a cross-sectional view of an exemplary fifth apparatusembodiment.

FIG. 93 is a perspective view of an exemplary sixth apparatusembodiment.

FIG. 94 is a cross-sectional view of an exemplary sixth apparatusembodiment.

FIG. 95 is a perspective view of an exemplary seventh apparatusembodiment.

FIG. 96 is a cross-sectional view of an exemplary seventh apparatusembodiment.

FIG. 97 is a perspective view of an exemplary eighth apparatusembodiment.

FIG. 98 is a cross-sectional view of an exemplary eighth apparatusembodiment.

FIG. 99 is a plan (or top) view illustrating an exemplary secondelectrode structure of a first conductive layer for an exemplaryapparatus embodiment.

FIG. 100 is a perspective view of third and fourth exemplary systemembodiments.

FIG. 101 is a plan (or top) view of exemplary ninth and tenth apparatusembodiments.

FIG. 102 is a cross-sectional view of an exemplary ninth apparatusembodiment.

FIG. 103 is a cross-sectional view of an exemplary tenth apparatusembodiment.

FIG. 104 is a perspective view illustrating an exemplary first surfacegeometry of an exemplary light emitting or absorbing region.

FIG. 105 is a perspective view illustrating an exemplary second surfacegeometry of an exemplary light emitting or absorbing region.

FIG. 106 is a perspective view illustrating an exemplary third surfacegeometry of an exemplary light emitting or absorbing region.

FIG. 107 is a perspective view illustrating an exemplary fourth surfacegeometry of an exemplary light emitting or absorbing region.

FIG. 108 is a perspective view illustrating an exemplary fifth surfacegeometry of an exemplary light emitting or absorbing region.

FIG. 109 is a photograph of an energized exemplary apparatus embodimentemitting light.

FIG. 110 is a scanning electron micrograph of an exemplary second diodeembodiment.

FIG. 111 is a scanning electron micrograph of a plurality of exemplarysecond diode embodiments.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

While the present invention is susceptible of embodiment in manydifferent forms, there are shown in the drawings and will be describedherein in detail specific exemplary embodiments thereof, with theunderstanding that the present disclosure is to be considered as anexemplification of the principles of the invention and is not intendedto limit the invention to the specific embodiments illustrated. In thisrespect, before explaining at least one embodiment consistent with thepresent invention in detail, it is to be understood that the inventionis not limited in its application to the details of construction and tothe arrangements of components set forth above and below, illustrated inthe drawings, or as described in the examples. Methods and apparatusesconsistent with the present invention are capable of other embodimentsand of being practiced and carried out in various ways. Also, it is tobe understood that the phraseology and terminology employed herein, aswell as the abstract included below, are for the purposes of descriptionand should not be regarded as limiting.

Exemplary embodiments of the invention provide a liquid and/or geldispersion and suspension of diodes 100, 100A, 100B, 100C, 100D, 100E,100F, 100G, 100H, 100I, 100J, 100K, 100L (collectively referred toherein and in the Figures as “diodes 100-100L”) which is capable ofbeing printed, and may be referred to equivalently herein as “diodeink”, it being understood that “diode ink” means and refers to a liquidand/or gel suspension of diodes or other two-terminal integratedcircuits, such as exemplary diodes 100-100L. As described in greaterdetail below, the diodes 100-100L themselves, prior to inclusion in thediode ink composition, are fully formed semiconductor devices which arecapable of functioning when energized to emit light (when embodied asLEDs) or provide power when exposed to a light source (when embodied asphotovoltaic diodes). An exemplary method of the invention alsocomprises a method of manufacturing diode ink which, as discussed ingreater detail below, disperses and suspends a plurality of diodes100-100L in a solvent and viscous resin or polymer mixture, in which thediodes 100-100L or other two-terminal integrated circuits are maintainedas dispersed and suspended for a substantial period of time, such as oneor more months under room temperature (25° C.) or refrigeratedconditions (5-10° C.), especially for the higher viscosity, moregelatinous compositions and the refrigeration-induced gelatinouscompositions, and which liquid or gel suspension is capable of beingprinted to manufacture LED-based devices and photovoltaic devices. Whilethe description is focused on diodes 100-100L as a type of two-terminalintegrated circuit, those having skill in the art will recognize thatother types of semiconductor devices may be substituted equivalently toform what is referred to more broadly as a “semiconductor device ink”,such as any type of transistor (field effect transistor (FET), metaloxide semiconductor field effect transistor (MOSFET), junction fieldeffect transistor (JFET), bipolar junction transistor (BJT), etc.),diac, triac, silicon controlled rectifier, etc., without limitation.

The diode ink (or semiconductor device ink) may be deposited, printed orotherwise applied to form any of various products discussed in greaterdetail below, such as an apparatus 300, 300A, 300B 300C, 300D, 700,700A, 700B, 720, 730, 740, 750, 760, 770 embodiment or system 350, 375,800, 810, or may be deposited, printed or otherwise applied to anyproduct of any kind or to form any product of any kind, includingsignage or indicia for product packaging, such as a consumer product, apersonal product, a business product, an industrial product, anarchitectural product, a building product, etc.

FIG. 1 is a perspective view illustrating an exemplary first diode 100embodiment. FIG. 2 is a plan (or top) view illustrating the exemplaryfirst diode 100 embodiment. FIG. 3 is a cross-sectional view (throughthe 10-10′ plane of FIG. 2) illustrating the exemplary first diode 100embodiment. FIG. 4 is a perspective view illustrating an exemplarysecond diode 100A embodiment. FIG. 5 is a plan (or top) viewillustrating the exemplary second diode 100A embodiment. FIG. 6 is aperspective view illustrating an exemplary third diode 100B embodiment.FIG. 7 is a plan (or top) view illustrating the exemplary third diode100B embodiment. FIG. 8 is a perspective view illustrating an exemplaryfourth diode 100C embodiment. FIG. 9 is a plan (or top) viewillustrating the exemplary fourth diode 100C embodiment. FIG. 10 is across-sectional view (through the 20-20′ plane of FIGS. 5, 7, 9)illustrating exemplary second, third and/or fourth diode 100A, 100B,100C embodiments. FIG. 11 is a perspective view illustrating exemplaryfifth and sixth diode 100D, 100E embodiments. FIG. 12 is a plan (or top)view illustrating the exemplary fifth and sixth diode 100D, 100Eembodiments. FIG. 13 is a cross-sectional view (through the 40-40′ planeof FIG. 12) illustrating the exemplary fifth diode 100D embodiment. FIG.14 is a cross-sectional view (through the 40-40′ plane of FIG. 12)illustrating the exemplary sixth diode 100E embodiment. FIG. 15 is aperspective view illustrating an exemplary seventh diode 100Fembodiment. FIG. 16 is a plan (or top) view illustrating the exemplaryseventh diode 100F embodiment. FIG. 17 is a cross-sectional view(through the 42-42′ plane of FIG. 16) illustrating the exemplary seventhdiode 100F embodiment. FIG. 18 is a perspective view illustrating anexemplary eighth diode 100G embodiment. FIG. 19 is a plan (or top) viewillustrating the exemplary eighth diode 100G embodiment. FIG. 20 is across-sectional view (through the 43-43′ plane of FIG. 19) illustratingthe exemplary eighth diode 100G embodiment. FIG. 21 is a perspectiveview illustrating an exemplary tenth diode 100K embodiment. FIG. 22 is across-sectional view (through the 47-47′ plane of FIG. 21) illustratingthe exemplary tenth diode 100K embodiment. FIG. 23 is a perspective viewillustrating an exemplary eleventh diode 100L embodiment. FIG. 24 is across-sectional view (through the 48-48′ plane of FIG. 23) illustratingthe exemplary eleventh diode 100L embodiment. Cross-sectional views ofninth, twelfth and thirteenth diode 100H, 100I, and 100J embodiments areillustrated in FIGS. 44, 50, and 66, respectively, as part ofillustrations of exemplary fabrication processes. FIG. 110 is a scanningelectron micrograph of an exemplary second diode 100A embodiment. FIG.111 is a scanning electron micrograph of a plurality of exemplary seconddiode 100A embodiments.

In the perspective and plan (or top) view diagrams, FIGS. 1, 2, 4-9, 11,12, 15, 16, 18, 19, 21 and 23, illustration of an outer passivationlayer 135 has been omitted in order to provide a view of otherunderlying layers and structures which would otherwise be covered bysuch a passivation layer 135 (and therefore not visible). Thepassivation layer 135 is illustrated in the cross-sectional views ofFIGS. 3, 10, 13, 14, 17, 20, 22, 24, 44, 50, 57, 62, 63, and 66-69, andthose having skill in the electronic arts will recognize that fabricateddiodes 100-100L generally will include at least one such passivationlayer 135. In addition, referring to FIGS. 1-69, 74, 76-85, and 87-103,those having skill in the art will also recognize that the variousFigures are for purposes of description and explanation, and are notdrawn to scale.

As described in greater detail below, the exemplary first throughthirteenth diode embodiments 100-100L differ primarily in the shapes,materials, doping and other compositions of the substrates 105 andwafers 150, 150A which may be utilized; the fabricated shape of thelight emitting region of the diode; the depth and locations of vias(130, 131, 132, 133, 134, 136) (such as shallow or “blind”, deep or“through”, center, peripheral, and perimeter); having a first terminal125 or both a first and second terminal 125, 127 on a first (top orfront) side; the use and size of back-side (second side) metallization(122) to form a first terminal 125 or a second terminal 127; the shapes,extent and locations of other contact metals; and may also differ in theshapes or locations of other features, as described in greater detailbelow. Exemplary methods and method variations for fabricating theexemplary diodes 100-100L are also described below. One or more of theexemplary diodes 100-100L are also available from and may be obtainedthrough NthDegree Technologies Worldwide, Inc. of Tempe, Ariz., USA.

Referring to FIGS. 1-24, exemplary diodes 100-100L are formed using asubstrate 105, such as a heavily-doped n+ (n plus) or p+ (p plus)substrate 105, e.g., a heavily doped n+ or p+ silicon substrate, whichmay be a silicon wafer or may be a more complex substrate or wafer, suchas comprising a silicon substrate (105) on insulator (“SOI”), or agallium nitride (GaN) substrate 105 on a sapphire (106) wafer 150A(illustrated in FIGS. 11-20), for example and without limitation. Othertypes of substrates (and/or wafers forming or having a substrate) 105may also be utilized equivalently, including Ga, GaAs, GaN, SiC, SiO₂,sapphire, organic semiconductor, etc., for example and withoutlimitation, and as discussed in greater detail below. Accordingly,reference to a substrate 105 or 105A should be understood broadly toalso include any types of substrates, such as n+ or p+ silicon, n+ or p+GaN, such as a n+ or p+ silicon substrate formed using a silicon wafer150 or the n+ or p+ GaN fabricated on a sapphire wafer 105A (describedbelow with reference to FIGS. 11-20 and 38-50). In the embodimentsillustrated in FIGS. 21-24, negligible to no substrate 105, 105A (andbuffer layer 145) has remained following substrate removal duringfabrication (leaving a complex GaN heterostructure in place, discussedin greater detail below), and either substrate 105, 105A may beutilized, for example and without limitation. When embodied usingsilicon, the substrate 105 typically has a <111> or <110> crystalstructure or orientation, although other crystalline structures may beutilized equivalently. An optional buffer layer 145 is typicallyfabricated on a silicon substrate 105, such as aluminum nitride orsilicon nitride, to facilitate subsequent fabrication of GaN layershaving a different lattice constant.

GaN layers are fabricated over the buffer layer 145, such as throughepitaxial growth, to form a complex GaN heterostructure, illustratedgenerally as n+ GaN layer 110, quantum well region 185, and p+ GaN layer115. In other embodiments, a buffer layer 145 is not or may not beutilized, such as when a complex GaN heterostructure (n+ GaN layer 110,quantum well region 185, and p+ GaN layer 115) is fabricated over a GaNsubstrate 105 (or directly over a sapphire (106) wafer 105A), asillustrated in FIGS. 15-17 as a more specific option. Those having skillin the electronic arts will understand that there may by many quantumwells within and potentially multiple p+, n+, other GaN layers with awide variety of dopants, and possibly non-GaN layers with any of variousdopants, to form a light emitting (or light absorbing) region 140, withn+ GaN layer 110, quantum well region 185, and p+ GaN layer 115 beingmerely illustrative and providing a generalized or simplifieddescription of a complex GaN heterostructure or any other semiconductorstructure forming one or more light emitting (or light absorbing)regions 140. Those having skill in the electronic arts will alsounderstand that the locations of the n+ GaN layer 110 and p+ GaN layer115 may be the same or may be reversed equivalently, such as for use ofa p+ silicon or GaN substrate 105, and that other compositions andmaterials may be utilized to form one or more light emitting (or lightabsorbing) regions 140 (many of which are described below), and all suchvariations are within the scope of the disclosure. While described withreference to GaN as a set of exemplary materials with differentcompounds, dopants and structures to form a light emitting or absorbingregion 140, those having skill in the art will recognize that any othersuitable semiconductor material may be utilized equivalently and iswithin the scope of the disclosure. In addition, those having skill inthe art will recognize that any reference to GaN should not be construedas “pure” GaN but will be understood to mean and include all of thevarious other compounds, dopants and layers that may be utilized to forma light emitting or absorbing region 140 and/or which allow a lightemitting or absorbing region 140 to be deposited, including anyintermediate non-GaN layers.

It should also be noted that while many of the various diodes (of diodes100-100L) are discussed in which silicon and GaN may be or are theselected semiconductors, other inorganic or organic semiconductors maybe utilized equivalently and are within the scope of the disclosure.Examples of inorganic semiconductors include, without limitation:silicon, germanium, and mixtures thereof; titanium dioxide, silicondioxide, zinc oxide, indium-tin oxide, antimony-tin oxide, and mixturesthereof; II-VI semiconductors, which are compounds of at least onedivalent metal (zinc, cadmium, mercury and lead) and at least onedivalent non-metal (oxygen, sulfur, selenium, and tellurium) such aszinc oxide, cadmium selenide, cadmium sulfide, mercury selenide, andmixtures thereof; III-V semiconductors, which are compounds of at leastone trivalent metal (aluminum, gallium, indium, and thallium) with atleast one trivalent non-metal (nitrogen, phosphorous, arsenic, andantimony) such as gallium arsenide, indium phosphide, and mixturesthereof; and group IV semiconductors including hydrogen terminatedsilicon, carbon, germanium, and alpha-tin, and combinations thereof.

In addition to the GaN light emitting/absorbing region 140 (e.g., a GaNheterostructure deposited over a substrate 105 such as n+ or p+ siliconor deposited over GaN (105) on a silicon wafer 150 or sapphire (106)wafer 150A), the plurality of diodes 100-100L may be comprised of anytype of semiconductor element, material or compound, such as silicon,gallium arsenide (GaAs), gallium nitride (GaN), or any inorganic ororganic semiconductor material, and in any form, including GaP, InAlGaP,InAlGaP, AlInGaAs, InGaNAs, AlInGASb, also for example and withoutlimitation. Also in addition, the wafer utilized to fabricate thetwo-terminal integrated circuits also may be of any type or kind, suchas silicon, GaAs, GaN, sapphire, silicon carbide, also for example andwithout limitation.

The scope of this disclosure, therefore, should be understood toencompass any epitaxial or compound semiconductor on a semiconductorsubstrate, including without limitation any LED or photovoltaicsemiconductor fabricated using a semiconductor substrate, of any kind,which is known or becomes known in the art.

In various exemplary embodiments, the n+ or p+ substrate 105 conductscurrent, which flows to the n+ GaN layer 110 as illustrated. Again, itshould be noted that any of the various illustrated layers of the lightemitting or absorbing region 140 equivalently may be reversed or ordereddifferently, such as reversing the locations of the illustrated n+ andp+ GaN layers 110, 115. The current flow path is also through a metallayer forming one or more vias (130) (which may also be utilized toprovide an electrical bypass of a very thin (about 25 Angstroms) bufferlayer 145 between the n+ or p+ substrate 105 and the n+ GaN layer 110).Additional types of vias 131-134 and 136 which provide other connectionsto conductive layers are described below. One or more metal layers 120,illustrated as two (or more) separately deposited metal layers 120A and120B (which also may be used to form vias (130, 131, 132, 133, 134,136)) provides an ohmic contact with the p+ GaN layer 115, with thesecond additional metal layer 120B such as die metal utilized to form a“bump” or protruding structure, with metal layers 120A, 120B forming afirst electrical terminal (or contact) 125 or second terminal 127 forvarious diodes 100-100L. Additional metal layers may also be utilized asdiscussed below. For the illustrated exemplary diode 100, 100A, 100B,100C embodiments, electrical terminal 125 may be the only ohmic,metallic terminal formed on the diodes 100, 100A, 100B, 100C duringfabrication for subsequent power (voltage) delivery (for LEDapplications) or reception (for photovoltaic applications), with the n+or p+ substrate 105 utilized to provide the second electrical terminalfor a diode 100, 100A, 100B, 100C for power delivery or reception. Itshould be noted that electrical terminal 125 and the n+ or p+ substrate105 are on opposing sides, top (first side) and bottom (or back, secondside) respectively, and not on the same side, of a diode 100, 100A,100B, 100C. As an option for these diode 100, 100A, 100B, 100Cembodiments and as illustrated for other exemplary diode embodiments, anoptional, second ohmic, metallic terminal 127 is formed using metalliclayer 122 on the second, back side of a diode (e.g., diode 100D, 100F,100G, 100J). As an option for the diode 100K embodiment, illustrated inFIGS. 21 and 22, a first ohmic, metallic terminal 125 is formed usingmetallic layer 122 on the second, back side of a diode 100K, with thediode 100K then flipped over or inverted for use. As another option,illustrated in FIGS. 23 and 24 for exemplary diode 100L, first terminal125 and second terminal 127 are both on the same, first (top) side ofthe diode 100L. Silicon nitride passivation 135 (or any other equivalentpassivation) is utilized, among other things, for electrical insulation,environmental stability, and possibly additional structural integrity.Not separately illustrated, a plurality of trenches 155 were formedduring fabrication along the lateral sides of the diodes 100-100L, asdiscussed below, which are utilized both to separate the diodes 100-100Lfrom each other on a wafer 150, 150A (singulate), and to separate thediodes 100-100L from the remainder of the wafer 150, 150A.

FIGS. 1-24 also illustrate some of the various shapes and form factorsof the one or more light emitting (or light absorbing) regions 140,illustrated as a GaN heterostructure (n+ GaN layer 110, quantum wellregion 185, and p+ GaN layer 115) and the various shapes and formfactors of the substrate 105 and/or complex GaN heterostructure. Also asillustrated, while an exemplary diode 100-100L is substantiallyhexagonal in the x-y plane (with curved or arced lateral sides 121,concave or convex (or both, forming a more complex sigmoidal shape), asdiscussed in greater detail below), to provide greater device densityper silicon wafer, other diode shapes and forms are consideredequivalent and within the scope of the claimed invention, such assquare, round, oval, elliptical, rectangular, triangular, octagonal,circular, etc. Also as illustrated in the exemplary embodiments, thehexagonal lateral sides 121 may also be curved or arced slightly, suchas convex (FIGS. 1, 2, 4, 5) or concave (FIGS. 6-9), such that whenreleased from the wafer and suspended in liquid, the diodes 100-100L mayavoid adhering or sticking to one another. In addition, for apparatus300, 300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740, 750, 760,770 fabrication, the relatively small thickness of the diodes 100-100Lis utilized to prevent individual die (individual diodes 100-100L) fromstanding on their lateral sides or edges (121). Also as illustrated inthe exemplary embodiments, the hexagonal lateral sides 121 may also becurved or arced slightly, to be both convex about the center or centralportion of each side 121 and concave peripherally/laterally to form amore complex sigmoidal shape (overlapping double “S” shape) resulting incomparatively pointed or projecting vertices 114 (FIGS. 11-24), suchthat when released from the wafer and suspended in liquid, the diodes100-100L also may avoid adhering or sticking to one another and may pushoff one another when rolling or moving against another diode). Thevariations from a flat surface topology for the diodes 100-100L (i.e., anon-flat surface topology) also helps to prevent the die from adheringto one another when suspended in a liquid or gel. Again, also forapparatus 300, 300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740,750, 760, 770 fabrication, the relatively small thickness or height ofthe diodes 100-100L (or of the light emitting regions for diodes 100Kand 100L) (in comparison to their lateral dimensions (diameters orwidths/lengths), tends to prevent individual die (individual diodes100-100L) from standing on their lateral sides or edges (121).

Various shapes and form factors of the light emitting (or lightabsorbing) regions 140 (n+ GaN layer 110, quantum well region 185 and p+GaN layer 115) are also illustrated, with FIGS. 1-3 illustrating asubstantially circular or disk-shaped light emitting (or lightabsorbing) region 140 (n+ GaN layer 110, quantum well region 185 and p+GaN layer 115), and with FIGS. 4 and 5 illustrating a substantiallytorus-shaped (or toroidal) light emitting (or light absorbing) region140 (n+ GaN layer 110, quantum well region 185 and p+ GaN layer 115)with the second metal layer 120B extending into the center of the toroid(and potentially providing a reflective surface). In FIGS. 6 and 7, thelight emitting (or light absorbing) region 140 (n+ GaN layer 110,quantum well region 185 and p+ GaN layer 115) has a substantiallycircular inner (lateral) surface and a substantially lobed outer(lateral) surface, while in FIGS. 8 and 9, the light emitting (or lightabsorbing) region 140 (n+ GaN layer 110, quantum well region 185 and p+GaN layer 115) also has a substantially circular inner (lateral) surfacewhile the outer (lateral) surface is substantially stellate- orstar-shaped. In FIGS. 11-24, the one or more light emitting (or lightabsorbing) regions 140 have a substantially hexagonal (lateral) surface(which may or may not extend to the perimeter of the die) and may have(at least partially) a substantially circular or elliptical inner(lateral) surface. In other exemplary embodiments not separatelyillustrated, there may be multiple light emitting (or light absorbing)regions 140, which may be continuous or which may be spaced apart on thedie. These various configurations of the one or more light emitting (orlight absorbing) regions 140 (n+ GaN layer 110, quantum well region 185and p+ GaN layer 115) having a circular inner surface may be implementedto increase the potential for light output (for LED applications) andlight absorption (for photovoltaic applications). As discussed ingreater detail below, the interior and/or exterior surfaces of any ofthe n+ GaN layers 110 or p+ GaN layers 115 may also have any of varioussurface textures or surface geometries, for example and withoutlimitation.

In an exemplary embodiment, the first terminal 125 (or second terminal127 for diode 100K) is comprised of one or more metal layers 120A, 120Band has a bump or protruding structure, to allow a significant portionof a diode 100-100L to be covered by one or more insulating ordielectric layers (following formation of an electrical contact by afirst conductor 310 or 310A to the n+ or p+ silicon substrate 105 (or toa second terminal formed by metal layer 122, or to a second terminalformed by a metal layer 128)), while simultaneously providing sufficientstructure for contact with the electrical terminal 125 by one or moreother conductive layers, such as a second conductor 320 discussed below.In addition, the bump or protruding structure of terminal 125potentially may also be one of a plurality of factors affecting rotationof a diode 100-100L within the diode ink and its subsequent orientation(top up (forward bias) or bottom up (reverse bias)) in a fabricatedapparatus 300, 300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740,750, 760, 770 in addition to the curvature of the lateral sides 121 andthe thickness (height) of the lateral sides 121.

Referring to FIGS. 11-22, exemplary diodes 100D, 100E, 100F, 100G, 100K,in various combinations, illustrate several additional and optionalfeatures. As illustrated, metal layer 120B forming a bump or protrudingstructure typically fabricated of die metal is substantially elliptical(or oval) (and substantially hexagonal in FIG. 21) in its circumferencerather than substantially circular in circumference, although othershapes and form factors of the terminal 125 are also within the scope ofthe disclosure. In addition, the metal layer 120B forming a bump orprotruding structure may have two or more elongated extensions 124,which serve several additional purposes in apparatus 300, 300A, 300B,300C, 300D, 700, 700A, 700B, 720, 730, 740, 750, 760, 770 fabrication,such as facilitating electrical contact formation with a secondconductor 320 and facilitating flow of an insulating dielectric 315(and/or first conductor 310) off of the terminal 125 (metal layer 120Bor metal 122). The elliptical form factor also may allow for additionallight emission (or absorption) from or to light emitting (or lightabsorbing) region 140 along the major axis sides of the elliptical metallayer 120B forming a bump or protruding structure. Metal layer 120A,forming an ohmic contact with p+ GaN layer 115, which also may bedeposited as multiple layers in multiple steps, also has elongatedextensions over p+ GaN layer 115 for selected embodiments, illustratedas curved metal contact extensions 126 in FIGS. 11, 12, 15, 16, 18 and19, facilitating current conduction to the p+ GaN layer 115 whilesimultaneously allowing for (and not blocking excessively) the potentialfor light emission or light absorption by the light emitting (or lightabsorbing) regions 140. Innumerable other shapes of the metal contactextensions 126 may be utilized equivalently, such as a grid pattern,other curvilinear shapes, etc. While not separately illustrated, suchelongated metal contact extensions may also be utilized in the otherembodiments illustrated in FIGS. 1-10 and 21-24. Additional seed orreflective metal layers may also be utilized, as described in greaterdetail below.

Additional types of via structures (131, 132, 133, 134, 136) are alsoillustrated in FIGS. 11-22, in addition to the peripheral (i.e., offcenter), comparatively shallow or “blind” via 130 previously describedwhich extends through the buffer layer 145 and into the substrate 105but not comparatively deeply into or through the substrate 105 in thefabricated diode 100, 100A, 100B, 100C. As illustrated in FIG. 13 (andFIGS. 44, 66), a center (or centrally located), comparatively deep,“through” via 131 extends completely through the substrate 105, and isutilized to make an ohmic contact with the n+ GaN layer 110 and toconduct current (or otherwise make an electrical contact) between thesecond (back) side metal layer 122 and the n+ GaN layer 110. Asillustrated in FIG. 22, a center (or centrally located), comparativelyless deep or more shallow, “through” via 136 extends completely throughthe complex GaN heterostructure (115, 185, 110), and is utilized to makean ohmic contact with the n+ GaN layer 110 and to conduct current (orotherwise make an electrical contact) between the second (back) sidemetal layer 122 and the n+ GaN layer 110. As illustrated in FIG. 14, acenter (or centrally located), comparatively shallow or blind via 132,also referred to as a “blind” via 132, extends through a buffer layer145 and into the substrate 105, and it utilized to make an ohmic contactwith the n+ GaN layer 110 and to conduct current (or otherwise make anelectrical contact) between the n+ GaN layer 110 and the substrate 105.As illustrated in FIGS. 15-17 and 49-50, a perimeter, comparatively deepor through via 133 extends along the lateral sides 121 (although coveredby passivation layer 135) from the n+ GaN layer 110 and to the second,back-side of the diode 100F, which in this embodiment also includessecond (back) side metal layer 122, completely around the lateral sidesof the substrate 105, and it utilized to make an ohmic contact with then+ GaN layer 110 and to conduct current (or otherwise make an electricalcontact) between the second (back) side metal layer 122 and the n+ GaNlayer 110. As illustrated in FIGS. 18-20, a peripheral, comparativelydeep, through via 134 extends completely through the substrate 105, andit utilized to make an ohmic contact with the n+ GaN layer 110 and toconduct current (or otherwise make an electrical contact) between thesecond (back) side metal layer 122 and the n+ GaN layer 110. Inembodiments which do not utilize a second (back) side metal layer 122,such through via structures (131, 133, 134, 136) may be utilized to makean electrical contact with the conductor 310A (in an apparatus 300,300A, 300B, 300C, 300D, 720, 730, 760) and to conduct current (orotherwise make an electrical contact) between the conductor 310A and then+ GaN layer 110. These through via structures (131, 133, 134, 136) areexposed on the second, back side of a diode 110D, 100F, 100G, 100Kduring fabrication, following singulation of the diodes through either aback side grind and polish or laser lift off (discussed below withreference to FIGS. 64 and 65), and may be left exposed or may be coveredby (and form an electrical contact with) second (back) side metal layer122 (as illustrated in FIG. 66).

The through via structures (131, 133, 134, 136) are considerablynarrower than typical vias known in the art. The through via structures(131, 133, 134) are on the order of about 7-9 microns deep (heightextending through the substrate 105) (and through via structure 136 ison the order of about 2-4 microns deep (height extending through thecomplex GaN heterostructure) and about 3-5 microns wide, compared toabout a 30 micron or greater width of traditional vias.

An optional second (back) side metal layer 122, forming a secondterminal or contact 127 or a first terminal 125 (diode 100K), is alsoillustrated in FIGS. 11-13, 17, 18, 20-22, 66, and 68. Such a secondterminal or contact 127, for example and without limitation, may beutilized to facilitate current conduction to the n+ GaN layer 110, suchas through the various through via structures (131, 133, 134, 136),and/or to facilitate forming an electrical contact with the conductor310A.

Referring to FIGS. 21-22, exemplary diode 100K illustrates severaladditional and optional features. FIG. 22 illustrates the fabricationlayers in cross section, for how the exemplary diode 100K is fabricated;the exemplary diode 100K is then flipped over or inverted to be rightside up as illustrated in FIG. 21, for use in exemplary apparatus 300,300A, 300B, 300C, 300D, 720, 730, 760 embodiments, with light beingemitted (in LED embodiments) through the upper n+ GaN layer 110.Accordingly, the first terminal 125 is formed from the second (back)side metal 122, the orientation of the n+ GaN layer 110 and p+ GaN layer115 are similarly reversed (n+ GaN layer 110 now being the upper layerin FIG. 21) (compared to the other embodiments 100-100J), with thesecond terminal 127 formed from one or more metal layers 120B. Verylittle to no substrate 105, 105A or a buffer layer 145 are illustrated,having been substantially removed during fabrication, leaving thecomplex GaN heterostructure in place (p+ GaN layer 115, quantum wellregion 185, and p+ GaN layer 115), and potentially some additional GaNlayer or substrate as well. The lateral sides or edges (121) arecomparatively thinner (or less thick) than other illustratedembodiments, under 10 microns, or more particularly between about 2 to 8microns, or more particularly between about 2 to 6 microns, or moreparticularly between about 2 to 4 microns, or more particularly 2.5 to3.5 microns, or about 3 microns, in exemplary embodiments, also toprevent individual diodes 100K from standing on their lateral sides oredges (121) during apparatus 300, 300A, 300B, 300C, 300D, 720, 730, 760fabrication.

The second (back) side metal 122 forming the first terminal 125 iscomparatively thick, between about 3 to 6 microns, or 4.5 to about 5.5microns, or about 5 microns, to provide a height of the diode 100Kbetween about 11 to 15 microns, or 12 to 14 microns, or about 13microns, in exemplary embodiments, to allow for deposition of dielectriclayers 315 and contact with a second conductor 320, and ellipticallyshaped, such as having a major axis about 14 microns and a minor axisabout 6 microns, for example and without limitation. The second (back)side metal 122 forming the first terminal 125 also does not extendacross the entire back side, for ease of back side alignment and diode100K singulation. The second terminal 127 is formed from metal layer(s)120B, and is also generally between about 3 to 6 microns in thickness,or 4.5 to about 5.5 microns in thickness, or about 5 microns inthickness, in exemplary embodiments. Also as illustrated, an insulating(passivation) layer 135A is also utilized to electrically insulate orisolate metal layer 120B from via 136, and may be deposited as aseparate step from the deposition of passivation (nitride) layer 135about the periphery, so is illustrated as 135A. In exemplaryembodiments, the width (side to side across the generally hexagonalshape, rather than vertex to vertex) of the diode 100K is between about10 to 50 microns, or more particularly between about 20 to 30 microns,or more particularly between about 22 to 28 microns, or moreparticularly between about 25 to 27 microns, or more particularlybetween about 25.5 to 26.5 microns, or more particularly about 26microns, for example and without limitation. Not separately illustrated,a metal layer 120A may also be included in fabrication second terminal127. During diode 100K fabrication (and in other exemplary diode100-100L embodiments), the top GaN layer (illustrated as p+ GaN layer115, but also may be other types of GaN layers, as illustrated in FIG.25) also may be metallized and alloyed with a very thin, opticallyreflective metal layer (illustrated as silver layer 103 in FIG. 25),and/or an optically transmissive metal layer (not separatelyillustrated) such as about a 100 Angstrom thickness of nickel-gold ornickel-gold-nickel, to facilitate formation of an ohmic contact (andpotentially provide for light reflection toward the n+ GaN layer 110),some of which is then removed with other GaN layers, such as during GaNmesa formation.

Referring to FIGS. 23 and 24, the exemplary eleventh diode 100Lembodiment differs from all of the other illustrated diode 100-100Kembodiments in having both first and second terminals 125, 127 on thesame (upper or top) side of the diode 100L. When utilized in exemplaryapparatus 700, 700A, 700B, 740, 750, 770 embodiments, light will beemitted (in LED embodiments) or absorbed (for photovoltaic embodiments)through the (lower) n+ GaN layer 110, typically through a substantiallyoptically transparent base 305A, as illustrated in FIGS. 80-82. As aconsequence of having both first and second terminals 125, 127 on thesame (upper or top) side of the diode 100L, this exemplary diode 100Ldoes not utilize any second (back) side metal 122, and generally doesnot require any of the various via structures previously discussed. Verylittle to no substrate 105, 105A or a buffer layer 145 are illustrated,also having been substantially removed during fabrication, leaving thecomplex GaN heterostructure in place (p+ GaN layer 115, quantum wellregion 185, and p+ GaN layer 115), and potentially some additional GaNas well. The lateral sides or edges (121) are also comparatively thinner(or less thick) than other illustrated embodiments, between about 2 to 4microns, or more particularly 2.5 to 3.5 microns, or about 3 microns, inexemplary embodiments, also to prevent individual diodes 100L fromstanding on their lateral sides or edges (121) during apparatus 700,700A, 700B, 740, 750, 770 fabrication. Not separately illustrated,during diode 100L fabrication (and in other exemplary diode 100-100Kembodiments), the top GaN layer (illustrated as p+ GaN layer 115, butalso may be other types of GaN layers, as illustrated in FIG. 25) alsomay be metallized and alloyed with a very thin, optically reflectivemetal layer (illustrated as silver layer 103 in FIG. 25), and/or anoptically transmissive metal layer (not separately illustrated) such asabout a 100 Angstrom thickness of nickel-gold or nickel-gold-nickel, tofacilitate formation of an ohmic contact (and potentially provide forlight reflection toward the n+ GaN layer 110), some of which is thenremoved with other GaN layers, such as during GaN mesa formation.

As illustrated in FIGS. 23 and 24, a GaN mesa (p+ GaN layer 115 andquantum well layer 185) is generally atypically shaped, somewhat like atriangle having flattened vertices (e.g., formed by providing aplurality (three) carve-out sections from a hexagonal or circularshape), to provide room on the upper surface of the n+ GaN layer 110 formetal contacts 128 (three are illustrated), which form second terminals127 on the upper or top side of the diode 100L. The GaN mesa generallyhas a height of between about 0.5 to 1.5 microns, or more particularly0.8 to 1.2 microns, or more particularly 0.9 to 1.1 microns, or moreparticularly about 1.0 microns in various exemplary embodiments. Themetal contacts 128 may be formed from via metal, approximately about0.75 to 1.5 microns in height, or more particularly about 0.9 to 1.1microns in height, or more particularly about 1.0 microns in height,such as about 100 Angstroms of titanium, 500 nm of aluminum, 500 nm ofnickel, and 100 nm of gold, and about 2.5 to 3.5 microns in width(measured radially). The first terminal 125, formed from metal layers120A and 120B, is shaped similarly to but smaller than the GaN mesa,generally having a height of between about 4 to 8 microns, or moreparticularly, 5 to 7 microns, or more particularly about 6 microns invarious exemplary embodiments, to allow for deposition of a firstconductor 310A in contact with metal contacts 128 and to allow fordeposition of dielectric layers 315, followed by contact of the firstterminal 125 with a second conductor 320 (illustrated in FIGS. 80-82).In this exemplary embodiment, the first terminal 125, formed from metallayers 120A and 120B, is also passivated (135), which in addition toproviding insulation and protection from contacting a first conductor310, may also serve to aid structural integrity of the first terminal125, which is useful to protect against various forces exerted in theprinting process. In exemplary embodiments, the width (side to sideacross the generally hexagonal shape, rather than vertex to vertex) ofthe diode 100L is between about 10 to 50 microns, or more particularlybetween about 20 to 30 microns, or more particularly between about 22 to28 microns, or more particularly between about 25 to 27 microns, or moreparticularly between about 25.5 to 26.5 microns, or more particularlyabout 26 microns. The height of the diode 100L generally is betweenabout 8 to 15 microns, or more particularly 9 to 12 microns, or moreparticularly about 10.5 to 11.5 microns, in exemplary embodiments.

It should be noted that the sizes of two-terminal devices more generallymay be larger, such as between about 10 to 75 microns in diameter (widthor length, depending on the shape, also measured face-to-face), andbetween about 5 to 25 microns in height.

FIG. 25 is a cross-sectional diagram through a portion of a complex GaNheterostructure (or GaN mesa) (n+ GaN layer 110, quantum well region185, p+ GaN layer 115) and metal layers 120A, 120B, illustratingoptional geometries and textures of the external and/or internalsurfaces of the complex GaN heterostructure (e.g., the surfaces ofeither the p+ GaN layer 115 or n+ GaN layer 110 or additional silver ormirror layer (103). Any of the various features illustrated in FIG. 25may be applied as an option to any of the various exemplary diodes100-100L. As illustrated in FIGS. 1-24, the external and/or internalsurfaces of the complex GaN heterostructure may be comparatively smooth.As illustrated in FIG. 25, any of the various external and/or internalsurfaces of the complex GaN heterostructure may be fabricated to haveany of various textures, geometries, mirrors, reflectors, or othersurface treatments. For example and without limitation, the external(upper or top) surface of the complex GaN heterostructure (illustratedas n+ GaN layer 110) may be etched to provide a surface roughness 112(illustrated as jagged conical or pyramidal structures), such as todecrease internal reflection and increase light extraction within thediode 100-100L embodiments. In addition, the external surfaces of thecomplex GaN heterostructure (e.g., the surfaces of either the p+ GaNlayer 115 or n+ GaN layer 110) may be masked and etched or otherwisefabricated to have various geometrical structures, such as domes or lensshapes 116; toroids, honeycomb, or waffle shapes 118; stripes 113, orother geometries (e.g., hexagons, triangles, etc.) 117, also for exampleand without limitation. Also in addition, the lateral sides 121 may alsoinclude various mirrors or reflectors 109, such as a dielectricreflector (e.g., SiO₂/Si₃N₄) or metallic reflectors. A wide variety ofsurface treatments and reflectors have been described, for example, inFujii et al. U.S. Pat. No. 7,704,763 issued Apr. 27, 2010, Chu et al.U.S. Pat. No. 7,897,420 issued Mar. 1, 2011, Kang et al. U.S. PatentApplication Publication No. 2010/0295014 A1 published Nov. 25, 2010, andShum U.S. Pat. No. 7,825,425 issued Nov. 2, 2010, all incorporatedherein by reference. Additional surface textures and geometries areillustrated in FIGS. 104-108.

Continuing to refer to FIG. 25, the internal surfaces of the complex GaNheterostructure (or more generally, diodes 100-100L) may also befabricated to have any of various textures, geometries, mirrors,reflectors, or other surface treatments. As illustrated, for example andwithout limitation, a reflective layer 103 may be utilized to providereflection of light out toward the exposed surface of the diodes100-100L and increased light extraction, such as by using a silver layerapplied during fabrication (prior to fabrication of metal layers 102A,102B), which may be either smooth (111) or have a textured (107)surface. Also for example and without limitation, an internal surface ofthe complex GaN heterostructure may also be smooth or have a texturedsurface, such as by using the additional layer 108 which may be, forexample, a diffuse n-type InGaN material. In addition, any of thesevarious optional surface geometry and textures may be utilized alone orin combination with each other, such as a double-diffuse structurehaving both the external surface texture 112 with an internal surfacetexture (107) and/or reflective layer 103. Various optional layers mayalso be utilized for additional reasons, such as to provide better ohmiccontact using an n-type InGaN material in a layer 108, independently ofany surface treatment which may or may not be utilized.

The diodes 100-100L are generally less than about 450 microns in alldimensions, and more specifically less than about 200 microns in alldimensions, and more specifically less than about 100 microns in alldimensions, and more specifically less than 50 microns in alldimensions. In the illustrated exemplary embodiments, the diodes100-100L are generally on the order of about 10 to 50 microns in width,or more specifically about 20 to 30 microns in width, and about 5 to 25microns in height, or more particularly between 5 to 15 microns inheight, or from about 25 to 28 microns in diameter (measured side faceto face rather than apex to apex) and 10 to 15 microns in height. Inexemplary embodiments, the height of the diodes 100-100L excluding themetal layer 120B or 122 forming the bump or protruding structure (i.e.,the height of the lateral sides 121 including the GaN heterostructure),depending upon the embodiment, is on the order of about 2 to 15 microns,or more specifically about 2 to 4 microns, or more specifically 7 to 12microns, or more specifically 8 to 11 microns, or more specifically 9 to10 microns, or more specifically less than 10 to 30 microns, while theheight of the metal layer 120B forming the bump or protruding structureis generally on the order of about 3 to 7 microns. As the dimensions ofthe diodes are engineered to within a selected tolerance during devicefabrication, the dimensions of the diodes may be measured, for exampleand without limitation, using a light microscope (which may also includemeasuring software), a scanning electron microscope (SEM), or a HoribaLA-920 (e.g., using Fraunhofer diffraction and light scattering tomeasure particle sizes (and distributions of particle sizes) while theparticles are in a dilute solution, which could be in a diode ink or anyother liquid or gel. All sizes or other measurements of diodes 100-100Lshould be considered averages (e.g., mean and/or median) of a pluralityof diodes 100-100L, and will vary considerably depending upon theselected embodiment (e.g., diodes 110-100J, or 100K, or 100L, willgenerally all have different respective sizes).

The diodes 100-100L may be fabricated using any semiconductorfabrication techniques which are known currently or which are developedin the future. FIGS. 26-66 illustrate a plurality of exemplary methodsof fabricating exemplary diodes 100-100L and illustrate severaladditional exemplary diodes 100H, 100I and 100J (in cross-section).Those having skill in the art will recognize that many of the varioussteps of diode 100-100L fabrication may occur in any of various orders,may be omitted or included in other sequences, and may result ininnumerable diode structures, in addition to those illustrated. Forexample, FIGS. 38-44 illustrate creation of a diode 100H which includesboth central and peripheral through (or deep) vias 131 and 134,respectively, combining features of diodes 100D and 100G, with orwithout optional second (back) side metal layer 122, while FIGS. 45-50illustrate creation of a diode 100I which includes a perimeter via 133,with or without optional second (back) side metal layer 122, and whichmay be combined with the other illustrated fabrication steps to includecentral or peripheral through vias 131 and 134, for example, such as toform a diode 100F.

FIGS. 26, 27 and 29-37 are cross-sectional views illustrating anexemplary method of diode 100, 100A, 100B, 100C fabrication inaccordance with the teachings of the present invention, with FIGS. 26-29illustrating fabrication at the wafer 150 level and FIGS. 30-37illustrating fabrication at the diode 100, 100A, 100B, 100C level. Thevarious illustrated fabrication steps may also be utilized to form otherdiodes 100D-100L, with FIGS. 26-32 applicable to any of the diodes100-100L, depending upon the selected substrate 105, 105A. FIG. 26 andFIG. 27 are cross-sectional views of a wafer 150 (such as a siliconwafer) having a silicon dioxide (or “oxide”) layer 190. FIG. 28 is aplan (or top) view of a silicon wafer 150 having a silicon dioxide layer190 etched in a grid pattern. The oxide layer 190 (generally about 0.1microns thick) is deposited or grown over the wafer 150, as shown inFIG. 26. As illustrated in FIG. 27, through appropriate or standard maskand/or photoresist layers and etching as known in the art, portions ofthe oxide layer 190 have been removed, leaving oxide 190 in a gridpattern (also referred to as “streets”), as illustrated in FIG. 28.

FIG. 29 is a cross-sectional view of a wafer 150 (such as a siliconwafer) having a buffer layer 145, a silicon dioxide (or “oxide”) layer190, and GaN layers (typically epitaxially grown or deposited to athickness of about 1.25-2.50 microns in an exemplary embodiment,although lesser or greater thicknesses are also within the scope of thedisclosure), illustrated as polycrystalline GaN 195 over the oxide 190,and n+ GaN layer 110, quantum well region 185 and p+ GaN layer 115forming a complex GaN heterostructure as mentioned above. As indicatedabove, a buffer layer 145 (such as aluminum nitride or silicon nitrideand generally about 25 Angstroms thick) is deposited on the siliconwafer 150 to facilitate subsequent GaN deposition. The polycrystallineGaN 195 grown or deposited over the oxide 190 is utilized to reduce thestress and/or strain (e.g., due to thermal mismatch of the GaN and asilicon wafer) in the complex GaN heterostructure (n+ GaN layer 110,quantum well region 185 and p+ GaN layer 115), which typically has asingle crystal structure. Other equivalent methods within the scope ofthe invention to provide such stress and/or strain reduction, forexample and without limitation, include roughening the surface of thesilicon wafer 150 and/or buffer layer 145 in selected areas, so thatcorresponding GaN regions will not be a single crystal, or etchingtrenches in the silicon wafer 150, such that there is also no continuousGaN crystal across the entire wafer 150. Such street formation andstress reduction fabrication steps may be omitted in other exemplaryfabrication methods, such as when other substrates are utilized, such asGaN (a substrate 105) on a sapphire wafer 150A. The GaN deposition orgrowth to form a complex GaN heterostructure may be provided through anyselected process as known or becomes known in the art and/or may beproprietary to the device fabricator. In an exemplary embodiment, acomplex GaN heterostructure comprised of n+ GaN layer 110, quantum wellregion 185 and p+ GaN layer 115 is available from Blue Photonics Inc. ofWalnut, Calif., USA and other vendors, for example and withoutlimitation.

FIG. 30 is a cross-sectional view of a substrate 105 having buffer layer145 and the complex GaN heterostructure (n+ GaN layer 110, quantum wellregion 185 and p+ GaN layer 115) in accordance with the teachings of thepresent invention, illustrating a much smaller portion of the wafer 150(such as region 191 of FIG. 29), to illustrate fabrication of a singlediode 100-100L. Through appropriate or standard mask and/or photoresistlayers and etching as known in the art, the complex GaN heterostructure(n+ GaN layer 110, quantum well region 185 and p+ GaN layer 115) isetched to form a GaN mesa structure 187, as illustrated in FIGS. 31 and32, with FIG. 32 illustrating the GaN mesa structure 187A havingcomparatively more angled sides, which potentially may facilitate lightproduction and/or absorption. Other GaN mesa structures 187 may also beimplemented, such as a partially or substantially toroidal GaN mesastructure 187, as illustrated in FIGS. 10, 13, 14, 17, 20, 22, 39-44,and 66. Following the GaN mesa etch, also through appropriate orstandard mask and/or photoresist layers and etching as known or becomesknown in the art, a (shallow or blind) via etch is performed, asillustrated in FIG. 33, creating a comparatively shallow trench 186through the GaN layers and buffer layer 145 and into the siliconsubstrate 105.

Also through appropriate or standard mask and/or photoresist layers andetching as known in the art, metallization layers are then deposited,forming a metal contact 120A to p+ GaN layer 115 and forming vias 130,as illustrated in FIG. 34. In exemplary embodiments, several layers ofmetal are deposited, a first or initial layer to form an ohmic contactto p+ GaN layer 115, typically comprising two metal layers about 50 to200 Angstroms each, of nickel followed by gold, followed by annealing atabout 450-500° C. in an oxidizing atmosphere of about 20% oxygen and 80%nitrogen, resulting in nickel rising to the top with a layer of nickeloxide, and forming a metal layer (as part of 120A) having acomparatively good ohmic contact with the p+ GaN layer 115. As anotherexample, during diode 100L fabrication (and in other exemplary diode100-100K embodiments), the top GaN layer (illustrated as p+ GaN layer115, but also may be other types of GaN layers, as illustrated in FIG.25) also may be metallized and alloyed with a very thin, opticallyreflective metal layer (illustrated as silver layer 103 in FIG. 25),and/or an optically transmissive metal layer (not separatelyillustrated) such as about a 100 Angstrom thickness of nickel-gold ornickel-gold-nickel, to facilitate formation of an ohmic contact (andpotentially provide for light reflection toward the n+ GaN layer 110),some of which is then removed with other GaN layers, such as during GaNmesa formation. Another metallization layer may also be deposited, suchas to form thicker interconnect metal to contour and fully form metallayer 120A (e.g., for current distribution) and to form the vias 130. Inanother exemplary embodiment (illustrated in FIGS. 45-50), the metalcontact 120A forming an ohmic contact to p+ GaN layer 115 may be formedprior to the GaN mesa etch, followed by the GaN mesa etch, via etch,etc. Innumerable other metallization processes and correspondingmaterials comprising metal layers 120A and 120B are also within thescope of the disclosure, with different fabrication facilities oftenutilizing different processes and material selections. For example andwithout limitation, either or both metal layers 120A and 120B may beformed by deposition of titanium to form an adhesion or seed layer,typically 50-200 Angstroms thick, followed by deposition of 2-4 micronsof nickel and a thin layer or “flash” of gold (a “flash” of gold being alayer of about 50-500 Angstroms thick), 3-5 microns of aluminum,followed by nickel (about 0.5 microns, physical vapor deposition orplating) and a “flash” of gold, or by deposition of titanium, followedby gold, followed by nickel (typically 3-5 microns thick for 120B),followed by gold, or by deposition of aluminum followed by nickelfollowed by gold, etc. In addition, the height of the metal layer 120Bforming a bump or protruding structure may also be varied, typicallybetween about 3.5-5.5 microns in exemplary embodiments, depending uponthe thickness of the substrate 105 (e.g., about 7-8 microns of GaNversus about 10 microns of silicon), for the resulting diodes 100-100Lto have a substantially uniform height and form factor.

For subsequent singulation of the diodes 100-100L from each other andfrom the wafer 150, through appropriate or standard mask and/orphotoresist layers and etching as known in the art, as illustrated inFIG. 35 and other FIGS. 40 and 48, trenches 155 are formed around theperiphery of each diode 100-100L (e.g., also as illustrated in FIGS. 2,5, 7 and 9). The trenches 155 are generally about 3-5 microns wide and10-12 microns deep. Also using appropriate or standard mask and/orphotoresist layers and etching as known in the art, nitride passivationlayer 135 is then grown or deposited, as illustrated in FIG. 36,generally to a thickness of about 0.35-1.0 microns, such as byplasma-enhanced chemical vapor deposition (PECVD) of silicon nitride,for example and without limitation, followed by photoresist and etchingsteps to remove unwanted regions of silicon nitride. In other exemplaryembodiments, the side walls of such singulation trenches may or may notbe passivated. Through appropriate or standard mask and/or photoresistlayers and etching as known in the art, metal layer 120B having a bumpor protruding structure is then formed, typically having a height of 3-5microns tall, as illustrated in FIG. 37. In an exemplary embodiment,formation of metal layer 120B is performed in several steps, using ametal seed layer, followed by more metal deposition using electroplatingor a lift off process, removing the resist and clearing the field of theseed layer. Other than subsequent singulation of the diodes (in thiscase diodes 100, 100A, 100B, 100C) from the wafer 150, as describedbelow, the diodes 100, 100A, 100B, 100C are otherwise complete, and itshould be noted that these completed diodes 100, 100A, 100B, 100C haveonly one metal contact or terminal on the upper surface of each diode100, 100A, 100B, 100C (first terminal 125). As an option, a second(back) side metal layer 122 may be fabricated, as described below and asmentioned above with reference to other exemplary diodes, such as toform a second terminal 127.

FIGS. 38-44 illustrate another exemplary method of diode 100-100Lfabrication, with FIG. 38 illustrating fabrication at the wafer 150Alevel and FIGS. 39-44 illustrating fabrication at the diode 100-100Llevel. FIG. 38 is a cross-sectional view of a wafer 150A having asubstrate 105 and having a complex GaN heterostructure (n+ GaN layer110, quantum well region 185, and p+ GaN layer 115). In this exemplaryembodiment, a comparatively thick layer of GaN is grown or deposited (toform a substrate 105) on sapphire (106) (of the sapphire wafer 150A),followed by deposition or growth of the GaN heterostructure (n+ GaNlayer 110, quantum well region 185, and p+GaN layer 115).

FIG. 39 is a cross-sectional view of a substrate 105 having a thirdmesa-etched complex GaN heterostructure, illustrating a much smallerportion of the wafer 150A (such as region 192 of FIG. 38), to illustratefabrication of a single diode (e.g., diode 100H, 100K). Throughappropriate or standard mask and/or photoresist layers and etching asknown in the art, the complex GaN heterostructure (n+ GaN layer 110,quantum well region 185 and p+ GaN layer 115) is etched to form a GaNmesa structure 187B. Following the GaN mesa etch, also throughappropriate or standard mask and/or photoresist layers and etching asknown or becomes known in the art, a (through or deep) via trench and asingulation trench etch is performed, as illustrated in FIG. 40,creating one or more comparatively deep via trenches 188 through thenon-mesa portion of the GaN heterostructure (n+ GaN layer 110) andthough the GaN substrate 105 to the sapphire (106) of the wafer 150A andcreating singulation trenches 155 described above. As illustrated, acenter via trench 188 and a plurality of peripheral via trenches 188have been formed. For a diode 100K embodiment, a shallow or blind viaetch may also be performed in the center of the mesa structure 187B,without formation of any peripheral vias or trenches.

Also through appropriate or standard mask and/or photoresist layers andetching as known in the art, metallization layers are then deposited,forming a center through via 131 and a plurality of peripheral throughvias 134, which also form an ohmic contact with the n+ GaN layer 110, asillustrated in FIG. 41. In exemplary embodiments, several layers ofmetal are deposited to form the through vias 131, 134. For example,titanium and tungsten may be sputtered to coat the sides and bottom ofthe trenches 188, to form a seed layer, followed by plating with nickel,to form solid metal vias 131, 134.

Also through appropriate or standard mask and/or photoresist layers andetching as known in the art, metallization layers are then deposited,forming a metal layer 120A providing an ohmic contact to p+ GaN layer115, as illustrated in FIG. 42. In exemplary embodiments, several layersof metal may be deposited as previously described to form metal layer120A and an ohmic contact to p+ GaN layer 115. Also using appropriate orstandard mask and/or photoresist layers and etching as known in the art,nitride passivation layer 135 is then grown or deposited, as illustratedin FIG. 43, generally to a thickness of about 0.35-1.0 microns, such asby plasma-enhanced chemical vapor deposition (PECVD) of silicon nitrideor silicon oxynitride, for example and without limitation, followed byphotoresist and etching steps to remove unwanted regions of siliconnitride. Through appropriate or standard mask and/or photoresist layersand etching as known in the art, metal layer 120B having a bump orprotruding structure is then formed, as illustrated in FIG. 44. In anexemplary embodiment, formation of metal layer 120B is performed inseveral steps, using a metal seed layer, followed by more metaldeposition using electroplating or a lift off process, removing theresist and clearing the field of the seed layer, also as describedabove. Other than subsequent singulation of the diodes (in this casediode 100H) from the wafer 150A, as described below, the diodes 100H areotherwise complete, and it should be noted that these completed diodes100H also have only one metal contact or terminal on the upper surfaceof each diode 100H (also a first terminal 125). Also as an option, asecond (back) side metal layer 122 may be fabricated, as described belowand as mentioned above with reference to other exemplary diodes, such asto form a second terminal 127.

FIGS. 45-50 illustrate another exemplary method of diode 100-100Lfabrication, with FIG. 45 illustrating fabrication at the wafer 150 or150A level and FIGS. 46-50 illustrating fabrication at the diode100-100L level. FIG. 45 is a cross-sectional view of a substrate 105having a buffer layer 145, a complex GaN heterostructure (n+ GaN layer110, quantum well region 185, and p+ GaN layer 115), and metallization(metal layer 120A) forming an ohmic contact with the p+ GaN layer. Asmentioned above, buffer layer 145 is typically fabricated when thesubstrate 105 is silicon (e.g., using a silicon wafer 150), and may beomitted for other substrates, such as a GaN substrate 105. In addition,sapphire 106 is illustrated as an option, such as for a thick GaNsubstrate 105 grown or deposited on a sapphire wafer 150A. Also asmentioned above, a metal layer 119 (as a seed layer for subsequentdeposition of metal layer 120A) has been deposited at an earlier step,following deposition or growth of the GaN heterostructure (n+ GaN layer110, quantum well region 185, and p+ GaN layer 115), rather than at alater step of diode fabrication. For example, metal layer 119 may benickel with a flash of gold having a total thickness of about a fewhundred Angstroms, or may be metallized and alloyed with a very thin,optically reflective metal layer (illustrated as silver layer 103 inFIG. 25) and/or an optically transmissive metal layer, such as about a100 Angstrom thickness of nickel-gold or nickel-gold-nickel, tofacilitate formation of an ohmic contact (and potentially provide forlight reflection toward the n+ GaN layer 110), some of which is thenremoved with other GaN layers, such as during GaN mesa formation.

FIG. 46 is a cross-sectional view of a substrate having a buffer layer,a fourth mesa-etched complex GaN heterostructure, and metallization(metal layer 119) forming an ohmic contact with the p+ GaN layer,illustrating a much smaller portion of the wafer 150 or 150A (such asregion 193 of FIG. 45), to illustrate fabrication of a single diode(e.g., diode 100I). Through appropriate or standard mask and/orphotoresist layers and etching as known in the art, the complex GaNheterostructure (n+ GaN layer 110, quantum well region 185 and p+ GaNlayer 115) (with metal layer 119) is etched to form a GaN mesa structure187C (with metal layer 119). Following the GaN mesa etch, also throughappropriate or standard mask and/or photoresist layers as known orbecomes known in the art, metallization is deposited (using any of theprocesses and metals previously described, such as titanium andaluminum, followed by annealing) to form metal layer 120A and also toform a metal layer 129 having an ohmic contact with the n+ GaN layer110, as illustrated in FIG. 47.

Following the metallization, also through appropriate or standard maskand/or photoresist layers and etching as known or becomes known in theart, a singulation trench etch is performed, as illustrated in FIG. 48,through the non-mesa portion of the GaN heterostructure (n+ GaN layer110) and though or comparatively deeply into the substrate 105 (e.g.,through the GaN substrate 105 to the sapphire (106) of the wafer 150A orthrough part of the silicon substrate 105 as previously described) andcreating singulation trenches 155 described above.

Also through appropriate or standard mask and/or photoresist layers andetching as known in the art, metallization layers are then depositedwithin trenches 155, forming a through or deep perimeter via 133(providing conduction around the entire outside or lateral perimeter ofthe diode (1004 which also form an ohmic contact with the n+ GaN layer110, as illustrated in FIG. 49. In exemplary embodiments, several layersof metal also may be deposited to form the through perimeter via 133.For example, titanium and tungsten may be sputtered to coat the sidesand bottom of the trenches 155, to form a seed layer, followed byplating with nickel, to form a solid metal perimeter via 133.

Again also using appropriate or standard mask and/or photoresist layersand etching as known in the art, nitride passivation layer 135 is thengrown or deposited, as illustrated in FIG. 50, generally to a thicknessof about 0.35-1.0 microns, such as by plasma-enhanced chemical vapordeposition (PECVD) of silicon nitride, for example and withoutlimitation, followed by photoresist and etching steps to remove unwantedregions of silicon nitride. Through appropriate or standard mask and/orphotoresist layers and etching as known in the art, metal layer 120Bhaving a bump or protruding structure is then formed as previouslydescribed, as illustrated in FIG. 50. Other than subsequent singulationof the diodes (in this case diode 100I) from the wafer 150 or 150A, asdescribed below, the diodes 100I are otherwise complete, and it shouldbe noted that these completed diodes 100I also have only one metalcontact or terminal on the upper surface of each diode 100I (also afirst terminal 125). Also as an option, a second (back) side metal layer122 may be fabricated, as described below and as mentioned above withreference to other exemplary diodes, such as to form a second terminal127.

FIGS. 51-57, 67 and 68 illustrate another exemplary method of diode 100Kfabrication, subsequent to the fabrication at the wafer 150 or 150Alevel illustrated in FIG. 45. FIG. 51 is a cross-sectional view of asubstrate having a buffer layer, a fifth mesa-etched complex GaNheterostructure 187D, and metallization forming an ohmic contact withthe p+ GaN layer. As mentioned above, buffer layer 145 is typicallyfabricated when the substrate 105 is silicon (e.g., using a siliconwafer 150), and may be omitted for other substrates, such as a GaNsubstrate 105. In addition, sapphire 106 is illustrated as an option,such as for a thick GaN substrate 105 grown or deposited on a sapphirewafer 150A, in which case the buffer layer 145 may be omitted. Also asmentioned above, a metal layer 119 (as a seed layer for subsequentdeposition of metal layer 120A) has been deposited at an earlier step,following deposition or growth of the GaN heterostructure (n+ GaN layer110, quantum well region 185, and p+ GaN layer 115), rather than at alater step of diode fabrication. For example, metal layer 119 may benickel with a flash of gold having a total thickness of about a fewhundred Angstroms, or may be metallized and alloyed with a very thin,optically reflective metal layer (illustrated as silver layer 103 inFIG. 25) and/or an optically transmissive metal layer, such as about a100 Angstrom thickness of nickel, nickel-gold or nickel-gold-nickel, tofacilitate formation of an ohmic contact with the p+ GaN layer 115 (andpotentially provide for light reflection toward the n+ GaN layer 110),some of which is then removed with other GaN layers, such as during GaNmesa formation. Through appropriate or standard mask and/or photoresistlayers and etching as known in the art, the complex GaN heterostructure(n+ GaN layer 110, quantum well region 185 and p+ GaN layer 115) (withmetal layer 119) is etched to form about a 1 micron deep GaN mesastructure 187D (with metal layer 119) having generally a toroidal shape,with an inner circular diameter of about 14 microns and an outer,generally hexagonal diameter of about 26 microns (measured sideface-to-face).

Following the GaN mesa etch (187D), also through appropriate or standardmask and/or photoresist layers and etching as known or becomes known inthe art, a blind or shallow via trench as illustrated in FIG. 52,creating a comparatively shallow, central via trench 211 into thenon-mesa portion of the GaN heterostructure (n+ GaN layer 110). Asillustrated, a circular, center via trench 211 about 2 microns deep hasbeen formed and 6 microns in diameter.

Through appropriate or standard mask and/or photoresist layers andetching as known in the art, metallization layers are then deposited,forming a center via 136, which also forms an ohmic contact with the n+GaN layer 110, as illustrated in FIG. 53. In exemplary embodiments,several layers of metal (e.g., via metal) are deposited to form thecenter via 136. For example, about 100 Angstroms of titanium and about1.5-2 microns of aluminum may be sputtered or plated to coat the sides,bottom, and part of the top of the trench 211, followed by alloying atabout 550° C., to form a solid metal via 136, about 10 microns in themaximum diameter on top of the n+ GaN layer 110. Also using appropriateor standard mask and/or photoresist layers and etching as known in theart, a first nitride passivation layer 135A is then grown or deposited,as illustrated in FIG. 54, generally to a thickness of about 0.35-1.0microns, or more particularly about 0.5 microns, and a maximum diameterof about 18 microns, such as by plasma-enhanced chemical vapordeposition (PECVD) of silicon nitride or silicon oxynitride, for exampleand without limitation, followed by photoresist and etching steps toremove unwanted regions of silicon nitride.

Also through appropriate or standard mask and/or photoresist layers andetching as known in the art, metallization layers are then deposited,forming a metal layer 120B having a bump or protruding structure forcontact to p+ GaN layer 115, as illustrated in FIG. 55, typically formedusing die metal. In exemplary embodiments, several layers of metal maybe deposited as previously described herein to form metal layers 120Aand/or 120B for contact to p+ GaN layer 115, and in the interest ofbrevity, will not be repeated here. In an exemplary embodiment, themetal layer 120B is generally hexagonal in shape and has a diameter ofabout 22 microns (measured side face-to-face), and is comprised of about100 Angstroms of nickel, about 4.5 microns of Aluminum, about 0.5microns of nickel, and about 100 nm of gold.

Following the metallization, also through appropriate or standard maskand/or photoresist layers and etching as known or becomes known in theart, a singulation trench etch is performed, as illustrated in FIG. 56,using methods described previously, through a portion of the GaNheterostructure (into but not completely through the n+ GaN layer 110),generally about 2 microns deep in an exemplary embodiment, and creatingsingulation trenches 155 described above.

A second nitride passivation layer 135 is then grown or deposited, asillustrated in FIG. 57, generally to a thickness of about 0.35-1.0microns, or more particularly about 0.5 microns, such as byplasma-enhanced chemical vapor deposition (PECVD) of silicon nitride orsilicon oxynitride, for example and without limitation. Then usingappropriate or standard mask and/or photoresist layers and etching asknown in the art, unwanted regions of silicon nitride are removed, suchas to clear the top of metal layer 102B, which will form a secondterminal 127.

Subsequent substrate removal, singulation and fabrication of a second(back) side metal layer 122 are described below with reference to FIGS.64, 65, 67 and 68.

FIGS. 58-63 and 69 illustrate another exemplary method of diode 100Lfabrication, subsequent to the fabrication at the wafer 150 or 150Alevel illustrated in FIG. 45. FIG. 58 is a cross-sectional view of asubstrate having a buffer layer, a sixth mesa-etched complex GaNheterostructure 187E, and metallization forming an ohmic contact withthe p+ GaN layer. As mentioned above, buffer layer 145 is typicallyfabricated when the substrate 105 is silicon (e.g., using a siliconwafer 150), and may be omitted for other substrates, such as a GaNsubstrate 105. In addition, sapphire 106 is illustrated as an option,such as for a thick GaN substrate 105 grown or deposited on a sapphirewafer 150A, in which case the buffer layer 145 may be omitted. Also asmentioned above, a metal layer 119 (as a seed layer for subsequentdeposition of metal layer 120A) has been deposited at an earlier step,following deposition or growth of the GaN heterostructure (n+ GaN layer110, quantum well region 185, and p+ GaN layer 115), rather than at alater step of diode fabrication. For example, metal layer 119 may benickel with a flash of gold having a total thickness of about a fewhundred Angstroms, or may be metallized and alloyed with a very thin,optically reflective metal layer (illustrated as silver layer 103 inFIG. 25) and/or an optically transmissive metal layer, such as about a100 Angstrom to about a 2.5 nm thickness of nickel, nickel-gold ornickel-gold-nickel, to facilitate formation of an ohmic contact with p+GaN layer 115 (and potentially provide for light reflection toward then+ GaN layer 110), some of which is then removed with other GaN layers,such as during GaN mesa formation. In an exemplary embodiment, about 2to 3 nm, or more particularly about 2.5 nm, of nickel or nickel and goldare deposited and alloyed at 500° C. to form metal layer 119 in ohmiccontact with p+ GaN layer 115. Through appropriate or standard maskand/or photoresist layers and etching as known in the art, the complexGaN heterostructure (n+ GaN layer 110, quantum well region 185 and p+GaN layer 115) (with metal layer 119) is etched to form about a 1 microndeep GaN mesa structure 187E (with metal layer 119) having the flattenedtriangular shape discussed above, with a first radius of about 8 micronsto the cut-out area leaving room for the contacts 128, and a secondradius of about 11 microns to the triangle apex/sides.

Following the GaN mesa etch (187E), also through appropriate or standardmask and/or photoresist layers and etching as known in the art, firstmetallization layers are then deposited, forming contacts 128, whichalso form an ohmic contact with the n+ GaN layer 110, as illustrated inFIG. 59. In exemplary embodiments, several layers of via metal aredeposited to form the contacts 128, which are utilized as a secondterminal 127. For example and without limitation, about 100 Angstroms oftitanium, about 500 nm of aluminum, 500 nm of nickel, and 100 nm of goldmay be sputtered or plated, to form solid metal contacts 128, each about1.1 microns thick, about 3 microns wide measured radially, and extendingabout the periphery of the n+ GaN layer 110 as illustrated in FIG. 23.In an exemplary embodiment, also as illustrated in FIG. 23, threecontacts 128 are formed.

Following the deposition of contacts 128, also through appropriate orstandard mask and/or photoresist layers as known or becomes known in theart, additional metallization is deposited (using any of the processesand metals previously described, such as titanium and aluminum, followedby annealing) to form metal layer 120A as part of the ohmic contact forp+ GaN layer 115, as illustrated in FIG. 60. For example, in anexemplary embodiment, about 200 nm of silver (forming a reflective ormirror layer), 200 nm of nickel, about 500 nm of aluminum, and 200 nm ofnickel may be sputtered or plated, to form centrally located metal layer120A about 1.1 microns thick and about 8 microns in diameter.

Also through appropriate or standard mask and/or photoresist layers andetching as known in the art, additional metallization layers are thendeposited, forming a metal layer 120B having a bump or protrudingstructure for contact to p+ GaN layer 115, as illustrated in FIG. 61,typically using die metal. In exemplary embodiments, several layers ofmetal may be deposited as previously described herein to form metallayers 120A and/or 120B for contact to p+ GaN layer 115, and in theinterest of brevity, will not be repeated here. In an exemplaryembodiment, the metal layer 120B generally has the flattened triangleshape illustrated in FIG. 23, with a first radius of about 6 microns tothe cut-out area (for the contacts 128), a second radius of about 9microns to the triangle apex/sides, which are each about 3.7 microns inwidth, and is comprised of about 200 nm of silver (also forming areflective or mirror layer over the p+ GaN layer 115), about 200 nm ofnickel, about 200 nm of aluminum, about 250 nm of nickel, about 200 nmof aluminum, about 250 nm of nickel, and about 100 nm of gold, eachadded as a successive layer, followed by alloying at 550° C. for about10 minutes in a nitrogen environment, for a total height of about 5microns, in addition to the about 1.1 micron height of metal layer 120A.It should be noted that this provide an approximately 5 micronseparation in height between the first and second terminals 125, 127.

A second nitride passivation layer 135 is then grown or deposited, asillustrated in FIG. 62, generally to a thickness of about 0.35-1.0microns, or more particularly about 0.5 microns, such as byplasma-enhanced chemical vapor deposition (PECVD) of silicon nitride orsilicon oxynitride, for example and without limitation. Then usingappropriate or standard mask and/or photoresist layers and etching asknown in the art, unwanted regions of silicon nitride are removed, suchas to clear the top of metal layer 102B, which will form a firstterminal 125.

Following the passivation, also through appropriate or standard maskand/or photoresist layers and etching as known or becomes known in theart, a singulation trench etch is performed, as illustrated in FIG. 63,using methods described previously, through a portion of the GaNheterostructure (into but not completely through the n+ GaN layer 110),generally about 2-3.5 microns deep in an exemplary embodiment, andcreating singulation trenches 155 described above.

Subsequent substrate removal and singulation are described below withreference to FIGS. 64, 65, 67 and 69.

Numerous variations of the methodology for fabrication of diodes100-100L may be readily apparent in light of the teachings of thedisclosure, all of which are considered equivalent and within the scopeof the disclosure. In other exemplary embodiments, such trench 155formation and (nitride) passivation layer formation may be performedearlier or later in the device fabrication process. For example,trenches 155 may be formed later in fabrication, after formation ofmetal layer 120B, and may leave exposed substrate 105, or may befollowed by a second passivation. Also for example, trenches 155 may beformed earlier in fabrication, such as after the GaN mesa etch, followedby deposition of (nitride) passivation layer 135. In the latter example,to maintain planarization during the balance of the device fabricationprocess, the passivated trenches 155 may be filled in with oxide,photoresist or other material (deposition of the layer followed byremoval of unwanted areas using a photoresist mask and etch or anunmasked etch process) or may be filled in (and potentially refilledfollowing metal contact 120A formation) with resist. In another example,silicon nitride 135 deposition (followed by mask and etch steps) may beperformed following the GaN mesa etch and before metal contact 120Adeposition.

FIG. 64 is a cross-sectional view illustrating an exemplary siliconwafer 150 embodiment having a plurality of diodes 100-100L adhered to aholding apparatus 160 (such as a holding, handle or holder wafer). FIG.65 is a cross-sectional view illustrating an exemplary diode sapphirewafer 150A embodiment adhered to a holding apparatus 160. As illustratedin FIGS. 64 and 65, the diode wafer 150, 150A containing a plurality ofunreleased diodes 100-100L (illustrated generally for purposes ofexplication and without any significant feature detail) is adhered,using any known, commercially available wafer adhesive or wafer bond165, to a holding apparatus 160 (such as a wafer holder) on the firstside of the diode wafer 150, 150A having the fabricated diodes 100-100L.As illustrated and as described above, singulation or individuationtrenches 155 between each diode 100-100L have been formed during waferprocessing, such as through etching, and is then utilized to separateeach diode 100-100L from adjacent diodes 100-100L without a mechanicalprocess such as sawing. As illustrated in FIG. 64, while the diode wafer150 is still adhered to the holding apparatus 160, the second, backside180 of the diode wafer 150 is then etched (e.g., wet or dry etched) ormechanically ground and polished to a level (illustrated as a dashedline), or both, either to expose the trenches 155, or to leave someadditional substrate which may then be removed through etching, forexample and without limitation. When sufficiently etched or ground andpolished, or both (and/or with any additional etching), each individualdiode 100-100L has been released from each other and any remaining diodewafer 150, while still adhered with the adhesive 165 to the holdingapparatus 160. As illustrated in FIG. 65, also while the diode wafer150A is still adhered to the holding apparatus 160, the second, backside180 of the diode wafer 150A is then exposed to laser light (illustratedas one or more laser beams 162) which then cleaves (illustrated as adashed line) the GaN substrate 105 from the sapphire 106 of the wafer150A (also referred to as laser lift-off), which also may be followed byany further chemical-mechanical polishing and any needed etching (e.g.,wet or dry etching), thereby releasing each individual diode 100-100Lfrom each other and the wafer 150A, while still adhered with theadhesive 165 to the holding apparatus 160. In this exemplary embodiment,the wafer 150A may then be ground and/or polished and re-used.

An epoxy bead (not separately illustrated) is also generally appliedabout the periphery of the wafer 150, to prevent non-diode fragmentsfrom the edge of the wafer from being released into the diode (100-100L)fluid during the diode release process discussed below.

FIG. 66 is a cross-sectional view illustrating an exemplary diode 100Jembodiment adhered to a holding apparatus. Following singulation of thediodes 100-100K (as described above with reference to FIGS. 64 and 65),and while the diodes 100-100K are still adhered with adhesive 165 to theholding apparatus 160, the second, back side of the diode 100-100K isexposed. As illustrated in FIG. 66, metallization may then be depositedto the second, back side, such as through vapor deposition (angled toavoid filling the trenches 155), forming second, back side metal layer122 and a diode 100J embodiment. Also as illustrated, diode 100J has onecenter through via 131 having an ohmic contact with the n+ GaN layer 110and contact with the second, back side metal layer 122 for currentconduction between the n+ GaN layer 110 and the second, back side metallayer 122. Exemplary diode 100D is quite similar, with exemplary diode100J having the second, back side metal layer 122 to form a secondterminal 127. As previously mentioned, the second, back side metal layer122 (or the substrate 105 or any of the various through vias 131, 133,134) may be used to make an electrical connection with a first conductor310 in an apparatus 300, 300A, 300B, 300C, 300D, 720, 730, 760 forenergizing the diode 100-100K.

FIG. 67 is a cross-sectional view illustrating an exemplary tenth diodeembodiment prior to back side metallization adhered to a holdingapparatus 160. As illustrated in FIG. 67, the exemplary diode-in-processhas been singulated, with any substrate 105, 105A removed as describedabove and also with an etching step (e.g., wet or dry etching), exposinga surface of the n+ GaN layer 110 and the via 136, leaving about a 2-6micron (or more particularly about a 2-4 micron, or more particularlyabout a 3 micron) depth of the complex GaN heterostructure. Usingappropriate or standard mask and/or photoresist layers and etching asknown in the art metallization is then deposited to the second, backside, such as through sputtering, plating or vapor deposition, formingsecond, back side metal layer 122 and a diode 100K embodiment asillustrated in FIG. 68. In an exemplary embodiment, the metal layer 122is elliptically-shaped, as illustrated in FIG. 21, generally about 12-16microns in width for the major axis, about 4-8 microns width for theminor axis, and about 4-6 microns in depth, or more particularlygenerally about 14 microns in width for the major axis, about 6 micronswidth for the minor axis, and about 5 microns in depth, and is comprisedof about 100 Angstroms of titanium, about 4.5 microns of aluminum, about0.5 microns of nickel, and 100 nm of gold. Also as illustrated for diode100K, what was originally a comparatively shallow center via is now athrough via 136 having an ohmic contact with the n+ GaN layer 110 andcontact with the second, back side metal layer 122 for currentconduction between the n+ GaN layer 110 and the second, back side metallayer 122. As previously mentioned, for this exemplary diode 100Kembodiment, the diode 100K is then flipped over or inverted, and thesecond, back side metal layer 122 forms a first terminal 125 and may beused to make an electrical connection with a second conductor 320 in anapparatus 300, 300A, 300B, 300C, 300D, 720, 730, 760 for energizing thediode 100K.

FIG. 69 is a cross-sectional view illustrating an exemplary eleventhdiode 100L embodiment adhered to a holding apparatus. As illustrated inFIG. 69, the exemplary diode 100L has been singulated, with anysubstrate 105, 105A removed as described above and with an etching step,exposing a surface of the n+ GaN layer 110, leaving about a 2-6 micron(or more particularly about a 3 to 5 micron, or more particularly abouta 4 to 5 micron, or more particularly about a 4.5 micron) depth of thecomplex GaN heterostructure.

Following singulation of the diodes 100-100L, they may be utilized, suchas to form a diode ink, discussed below with reference to FIGS. 74 and75.

It should also be noted that various surface geometries and/or texturesmay also be fabricated for any of the various diodes 100-100L, to helpreduce internal reflection and increase light extraction whenimplemented as LEDs. Any of these various surface geometries may alsohave any of the various surface textures previously discussed withreference to FIG. 25. FIG. 104 is a perspective view illustrating anexemplary first surface geometry of an exemplary light emitting orabsorbing region, implemented as a plurality of concentric rings ortoroidal shapes on the upper, light emitting (or absorbing) surface of adiode 100K. Such a geometry is typically etched into the second, backside of the diode 100K before or after the addition of the back sidemetal 122, through appropriate or standard mask and/or photoresistlayers and etching as known or becomes known in the art. FIG. 105 is aperspective view illustrating an exemplary second surface geometry of anexemplary light emitting or absorbing region, implemented as a pluralityof substantially curvilinear trapezoidal shapes on the upper, lightemitting (or absorbing) surface of a diode 100K. Such a geometry also istypically etched into the second, back side of the diode 100K before orafter the addition of the back side metal 122, also through appropriateor standard mask and/or photoresist layers and etching as known orbecomes known in the art.

FIG. 106 is a perspective view illustrating an exemplary third surfacegeometry of an exemplary light emitting or absorbing region, implementedas a plurality of substantially curvilinear trapezoidal shapes on thelower (or bottom), light emitting (or absorbing) surface of a diode100L. FIG. 107 is a perspective view illustrating an exemplary fourthsurface geometry of an exemplary light emitting or absorbing region,implemented as substantially star or stellate shapes on the lower (orbottom), light emitting (or absorbing) surface of a diode 100L. FIG. 108is a perspective view illustrating an exemplary fifth surface geometryof an exemplary light emitting or absorbing region, implemented as aplurality of substantially parallel bar or stripe shapes on the lower(or bottom), light emitting (or absorbing) surface of a diode 100L. Suchgeometries also are typically etched into the second, back side of thediode 100L as part of the substrate removal process and/or the diodesingulation process previously discussed with reference to FIG. 69,through appropriate or standard mask and/or photoresist layers andetching as known or becomes known in the art.

FIGS. 70, 71, 72 and 73 are flow diagrams illustrating exemplary first,second, third and fourth method embodiments for diode 100-100Lfabrication, respectively, and provide a useful summary. It should benoted that many of the steps of these methods may be performed in any ofvarious orders, and that steps of one exemplary method may also beutilized in the other exemplary methods. Accordingly, each of themethods will refer generally to fabrication of any of the diodes100-100L, rather than fabrication of a specific diode 100-100Lembodiment, and those having skill in the art will recognize which stepsmay be “mixed and matched” to create any selected diode 100-100Lembodiment.

Referring to FIG. 70, beginning with start step 240, an oxide layer isgrown or deposited on a semiconductor wafer, step 245, such as a siliconwafer. The oxide layer is etched, step 250, such as to form a grid orother pattern. A buffer layer and a light emitting or absorbing region(such as a GaN heterostructure) is grown or deposited, step 255, andthen etched to form a mesa structure for each diode 100-100L, step 260.The wafer 150 is then etched to form via trenches into the substrate 105for each diode 100-100L, step 265. One or more metallization layers arethen deposited to form a metal contact and vias for each diode 100-100L,step 270. Singulation trenches are then etched between diodes 100-100L,step 275. A passivation layer is then grown or deposited, step 280. Abump or protruding metal structure is then deposited or grown on themetal contact, step 285, and the method may end, return step 290. Itshould be noted that many of these fabrication steps may be performed bydifferent entities and agents, and that the method may include the othervariations and ordering of steps discussed above.

Referring to FIG. 71, beginning with start step 500, a comparativelythick GaN layer (e.g., 7-8 microns) is grown or deposited on a wafer,step 505, such as a sapphire wafer 150A. A light emitting or absorbingregion (such as a GaN hetero structure) is grown or deposited, step 510,and then etched to form a mesa structure for each diode 100-100L (on afirst side of each diode 100-100L), step 515. The wafer 150 is thenetched to form one or more through or deep via trenches and singulationtrenches into the substrate 105 for each diode 100-100L, step 520. Oneor more metallization layers are then deposited to form through vias foreach diode 100-100L, which may be center, peripheral or perimeterthrough vias (131, 134, 133, respectively), typically by depositing aseed layer, step 525, followed by additional metal deposition using anyof the methods described above. Metal is also deposited to form one ormore metal contacts to the GaN hetero structure (such as to the p+ GaNlayer 115 or to the n+ GaN layer 110), step 535, and to form anyadditional current distribution metal (e.g., 120A, 126), step 540. Apassivation layer is then grown or deposited, step 545, with areasetched or removed as previously described and illustrated. A bump orprotruding metal structure (120B) is then deposited or grown on themetal contact(s), step 550. The wafer 150A is then attached to a holdingwafer, step 555, and the sapphire or other wafer is removed (e.g.,through laser cleaving) to singulate or individuate the diodes 100-100L,step 560. Metal is then deposited on the second, back side of the diodes100-100L to form the second, back side metal layer 122, step 565, andthe method may end, return step 570. It also should be noted that manyof these fabrication steps may be performed by different entities andagents, and that the method may include the other variations andordering of steps discussed above.

Referring to FIG. 72, beginning with start step 600, a comparativelythick GaN layer (e.g., 7-8 microns) is grown or deposited on a wafer150, step 605, such as a sapphire wafer 150A. A light emitting orabsorbing region (such as a GaN heterostructure) is grown or deposited,step 610. Metal is deposited to form one or more metal contacts to theGaN heterostructure (such as to the p+ GaN layer 115 as illustrated inFIG. 45), step 615. The light emitting or absorbing region (such as theGaN hetero structure) with the metal contact layer (119) are then etchedto form a mesa structure for each diode 100-100L (on a first side ofeach diode 100-100L), step 620. Metal is deposited to form one or moremetal contacts to the GaN heterostructure (such as n+ metal contactlayer 129 to the n+ GaN layer 110 as illustrated in FIG. 47), step 625.The wafer 150A is then etched to form one or more through or deep viatrenches and/or singulation trenches into the substrate 105 for eachdiode 100-100L, step 630. One or more metallization layers are thendeposited to form through vias for each diode 100-100L, step 635, whichmay be center, peripheral or perimeter through vias (131, 134, 133,respectively), using any of the metal deposition methods describedabove. Metal is also deposited to form one or more metal contacts to theGaN heterostructure (such as the p+ GaN layer 115 or to the n+ GaN layer110), and to form any additional current distribution metal (e.g., 120A,126), step 640. If singulation trenches were not previously created (instep 630), then singulation trenches are etched, step 645. A passivationlayer is then grown or deposited, step 650, with areas etched or removedas previously described and illustrated. A bump or protruding metalstructure (120B) is then deposited or grown on the metal contact(s),step 655. The wafer 150, 150A is then attached to a holding wafer, step660, and the sapphire or other wafer is removed (e.g., through lasercleaving or back side grinding and polishing) to singulate orindividuate the diodes 100-100L, step 665. Metal is then deposited onthe second, back side of the diodes 100-100L to form the second, backside conductive (e.g., metal) layer 122, step 670, and the method mayend, return step 675. It also should be noted that many of thesefabrication steps may be performed by different entities and agents, andthat the method may include the other variations and ordering of stepsdiscussed above.

Referring to FIG. 73, beginning with start step 611, a comparativelythick GaN layer (e.g., 7-8 microns) is grown or deposited on a wafer150, step 611, such as a sapphire wafer 150A or over a buffer layer 145of a silicon wafer 150. A light emitting or absorbing region (such as aGaN heterostructure) is grown or deposited, step 616. Metal is depositedto form one or more metal contacts to the GaN heterostructure (such asto the p+ GaN layer 115 as illustrated in FIG. 45), step 621. The lightemitting or absorbing region (such as the GaN heterostructure) with themetal contact layer (119) are then etched to form a mesa structure foreach diode 100-100L (on a first side of each diode 100-100L), step 626.For a diode 100K embodiment, the GaN heterostructure is then etched toform a center via trench for each diode 100K, step 631, and otherwisestep 631 may be omitted. One or more metallization layers are thendeposited to form a center via 136 for each diode 100K or a metalcontact 128 for a diode 100L, using any of the metal deposition methodsdescribed above, step 636. For a diode 100K embodiment, a passivationlayer 135A is then grown or deposited, step 641, with areas etched orremoved as previously described and illustrated, and otherwise step 641may be omitted. Metal is also deposited to form one or more metalcontacts to the GaN heterostructure (such as the p+ GaN layer 115), suchas metal layer 120B or metal layers 120A and 120B, step 646. Ifsingulation trenches were not previously created, then singulationtrenches are etched, step 651. A passivation layer is then grown ordeposited, step 656, with areas etched or removed as previouslydescribed and illustrated. It should be noted that steps 656 and 651occur in an opposite order for diode 100L fabrication, with passivationoccurring followed by etching singulation trenches. The wafer 150, 150Ais then attached to a holding wafer, step 661, and the silicon, sapphireor other wafer is removed (e.g., through laser cleaving or back sidegrinding and polishing) to singulate or individuate the diodes 100-100L,step 666, with any additional GaN removal, such as through etching. Fora diode 100K embodiment, metal is then deposited on the second, backside of the diodes 100K to form the second, back side conductive (e.g.,metal) layer 122, step 671, and the method may end, return step 676. Italso should be noted that many of these fabrication steps may beperformed by different entities and agents, and that the method mayinclude the other variations and ordering of steps discussed above. Forexample, steps 611 and 612 may be carried out be a specialized vendor.

FIG. 74 is a cross-sectional view illustrating individual diodes100-100L (also illustrated generally for purposes of explication andwithout any significant feature detail) which are no longer coupledtogether on the diode wafer 150, 150A (as the second side of the diodewafer 150, 150A has now been ground or polished, cleaved (laserlift-off), and/or etched, to fully expose the singulation(individuation) trenches 155), but which are adhered with wafer adhesive165 to a holding apparatus 160 and suspended or submerged in a dish 175with wafer adhesive solvent 170. Any suitable dish 175 may be utilized,such as a petri dish, with an exemplary method utilizing apolytetrafluoroethylene (PTFE or Teflon) dish 175. The wafer adhesivesolvent 170 may be any commercially available wafer adhesive solvent orwafer bond remover, including without limitation 2-dodecene wafer bondremover available from Brewer Science, Inc. of Rolla, Mo. USA, forexample, or any other comparatively long chain alkane or alkene orshorter chain heptane or heptene. The diodes 100-100L adhered to theholding apparatus 160 are submerged in the wafer adhesive solvent 170for about five to about fifteen minutes, typically at room temperature(e.g., about 65° F.-75° F. or a higher temperature, and may also besonicated in exemplary embodiments. As the wafer adhesive solvent 170dissolves the adhesive 165, the diodes 100-100L separate from theadhesive 165 and holding apparatus 160 and mostly or generally sink tothe bottom of the dish 175, individually or in groups or clumps. Whenall or most diodes 100-100L have been released from the holdingapparatus 160 and have settled to the bottom of the dish 175, theholding apparatus 160 and a portion of the currently used wafer adhesivesolvent 170 are removed from the dish 175. More wafer adhesive solvent170 is then added (about 120-140 ml), and the mixture of wafer adhesivesolvent 170 and diodes 100-100L is agitated (e.g. using a sonicator oran impeller mixer) for about five to fifteen minutes, typically at roomor higher temperature, followed by once again allowing the diodes100-100L to settle to the bottom of the dish 175. This process is thenrepeated generally at least once more, such that when all or most diodes100-100L have settled to the bottom of the dish 175, a portion of thecurrently used wafer adhesive solvent 170 is removed from the dish 175and more (about 120-140 ml) wafer adhesive solvent 170 is then added,followed by agitating the mixture of wafer adhesive solvent 170 anddiodes 100-100L for about five to fifteen minutes, at room or highertemperature, followed by once again allowing the diodes 100-100L tosettle to the bottom of the dish 175 and removing a portion of theremaining wafer adhesive solvent 170. At this stage, a sufficient amountof any residual wafer adhesive 165 generally will have been removed fromthe diodes 100-100L, or the wafer adhesive solvent 170 process repeated,to no longer potentially interfere with the printing or functioning ofthe diodes 100-100L.

Removal of the wafer adhesive solvent 170 (having the dissolved waferadhesive 165), or of any of the other solvents, solutions or otherliquids discussed below, may be accomplished in any of various ways. Forexample, wafer adhesive solvent 170 or other liquids may be removed byvacuum, aspiration, suction, pumping, etc., such as through a pipette.Also for example, wafer adhesive solvent 170 or other liquids may beremoved by filtering the mixture of diodes 100-100L and wafer adhesivesolvent 170 (or other liquids), such as by using a screen or poroussilicon membrane having an appropriate opening or pore size. It shouldalso be mentioned that all of the various fluids used in the diode ink(and dielectric ink discussed below) are filtered to remove particleslarger than about 10 microns.

Diode Ink Example 1

-   -   A composition comprising:    -   a plurality of diodes 100-100L; and    -   a solvent.

Substantially all or most of the wafer adhesive solvent 170 is thenremoved. A solvent, and more particularly a polar solvent such asisopropyl alcohol (“IPA”) in an exemplary embodiment and for example, isadded to the mixture of wafer adhesive solvent 170 and diodes 100-100L,followed by agitating the mixture of IPA, wafer adhesive solvent 170 anddiodes 100-100L for about five to fifteen minutes, generally at roomtemperature (although a higher temperature may be utilizedequivalently), followed by once again allowing the diodes 100-100L tosettle to the bottom of the dish 175 and removing a portion of themixture of IPA and wafer adhesive solvent 170. More IPA is added(120-140 ml), and the process is repeated two or more times, namely,agitating the mixture of IPA, wafer adhesive solvent 170 and diodes100-100L for about five to fifteen minutes, generally at roomtemperature, followed by once again allowing the diodes 100-100L tosettle to the bottom of the dish 175, removing a portion of the mixtureof IPA and wafer adhesive solvent 170 and adding more IPA. In anexemplary embodiment, the resulting mixture is about 100-110 ml of IPAwith approximately 9-10 million diodes 100-100L from a four inch wafer(approximately 9.7 million diodes 100-100L per four inch wafer 150), andis then transferred to another, larger container, such as a PTFE jar,which may include additional washing of diodes into the jar withadditional IPA, for example. One or more solvents may be usedequivalently, for example and without limitation: water; alcohols suchas methanol, ethanol, N-propanol (“NPA”) (including 1-propanol,2-propanol (IPA), 1-methoxy-2-propanol), butanol (including 1-butanol,2-butanol (isobutanol)), pentanol (including 1-pentanol, 2-pentanol,3-pentanol), octanol, N-octanol (including 1-octanol, 2-octanol,3-octanol), tetrahydrofurfuryl alcohol (THFA), cyclohexanol, terpineol;ethers such as methyl ethyl ether, diethyl ether, ethyl propyl ether,and polyethers; esters such ethyl acetate, dimethyl adipate, propyleneglycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate,glycerin acetate; glycols such as ethylene glycols, diethylene glycol,polyethylene glycols, propylene glycols, dipropylene glycols, glycolethers, glycol ether acetates; carbonates such as propylene carbonate;glycerols such as glycerin; acetonitrile, tetrahydrofuran (THF),dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide(DMSO); and mixtures thereof. The resulting mixture of diodes 100-100Land a solvent such as IPA is a first example of a diode ink, as Example1 above, and may be provided as a stand-alone composition, for example,for subsequent modification or use in printing, also for example. Inother exemplary embodiments discussed below, the resulting mixture ofdiodes 100-100L and a solvent such as IPA is an intermediate mixturewhich is further modified to form a diode ink for use in printing, asdescribed below.

In various exemplary embodiments, the selection of a first (or second)solvent is based upon at least two properties or characteristics. Afirst characteristic of the solvent is its ability be soluble in or tosolubilize a viscosity modifier or an adhesive viscosity modifier suchas hydroxy propyl methylcellulose resin, methoxy propyl methylcelluloseresin, or other cellulose resin or methylcellulose resin. A secondcharacteristic or property is its evaporation rate, which should be slowenough to allow sufficient screen residence (for screen printing) of thediode ink or to meet other printing parameters. In various exemplaryembodiments, an exemplary evaporation rate is less than one (<1, as arelative rate compared with butyl acetate), or more specifically,between 0.0001 and 0.9999.

Diode Ink Example 2

-   -   A composition comprising:    -   a plurality of diodes 100-100L; and    -   a viscosity modifier.

Diode Ink Example 3

-   -   A composition comprising:    -   a plurality of diodes 100-100L; and    -   a solvating agent.

Diode Ink Example 4

-   -   A composition comprising:    -   a plurality of diodes 100-100L; and    -   a wetting solvent.

Diode Ink Example 5

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a solvent; and    -   a viscosity modifier.

Diode Ink Example 6

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a solvent; and    -   an adhesive viscosity modifier.

Diode Ink Example 7

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a solvent; and    -   a viscosity modifier;    -   wherein the composition is opaque when wet and substantially        optically transmissive or otherwise clear when dried.

Diode Ink Example 8

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a first, polar solvent;    -   a viscosity modifier; and    -   a second, nonpolar solvent (or rewetting agent).

Diode Ink Example 9

-   -   A composition comprising:    -   a plurality of diodes 100-100L, each diode of the plurality of        diodes 100-100L having a size less than 450 microns in any        dimension; and    -   a solvent.

Diode Ink Example 10

-   -   A composition comprising:    -   a plurality of diodes 100-100L; and    -   at least one substantially non-insulating carrier or solvent.

Diode Ink Example 11

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a solvent; and    -   a viscosity modifier;    -   wherein the composition has a dewetting or contact angle greater        than 25 degrees, or greater than 40 degrees.

Referring to Diode Ink Examples 1-11, there are a wide variety ofexemplary diode ink compositions within the scope of the presentinvention. Generally, as in Example 1, a liquid suspension of diodes(100-100L) comprises a plurality of diodes (100-100L) and a firstsolvent (such as IPA discussed above or N-propanol,1-methoxy-2-propanol, dipropylene glycol, 1-octanol (or more generally,N-octanol), or diethylene glycol discussed below); as in Examples 2, aliquid suspension of diodes (100-100L) comprises a plurality of diodes(100-100L) and a viscosity modifier (such those discussed below, whichmay also be an adhesive viscosity modifier as in Example 6); and as inExamples 3 and 4, a liquid suspension of diodes (100-100L) comprises aplurality of diodes (100-100L) and a solvating agent or a wettingsolvent (such as one of the second solvents discussed, below, e.g., adibasic ester). More particularly, such as in Examples 2, 5, 6, 7 and 8,a liquid suspension of diodes (100-100L) comprises a plurality of diodes(100-100L) (and/or plurality of diodes (100-100L) and a first solvent(such as N-propanol, 1-octanol, 1-methoxy-2-propanol, dipropyleneglycol, terpineol or diethylene glycol)), and a viscosity modifier (orequivalently, a viscous compound, a viscous agent, a viscous polymer, aviscous resin, a viscous binder, a thickener, and/or a rheologymodifier) or an adhesive viscosity modifier (discussed in greater detailbelow), to provide a diode ink having a viscosity between about 1,000centipoise (cps) and 25,000 cps at room temperature (about 25° C.) (orbetween about 20,000 cps to 60,000 cps at a refrigerated temperature(e.g., 5-10° C.)), such as an E-10 viscosity modifier described below,for example and without limitation. Depending upon the viscosity, theresulting composition may be referred to equivalently as a liquid or asa gel suspension of diodes or other two-terminal integrated circuits,and any reference to liquid or gel herein shall be understood to meanand include the other.

In addition, the resulting viscosity of the diode ink will generallyvary depending upon the type of printing process to be utilized and mayalso vary depending upon the diode composition, such as a siliconsubstrate 105 or a GaN substrate 105. For example, a diode ink forscreen printing in which the diodes 100-100L have a silicon substrate105 may have a viscosity between about 1,000 centipoise (cps) and 25,000cps at room temperature, or more specifically between about 6,000centipoise (cps) and 15,000 cps at room temperature, or morespecifically between about 6,000 centipoise (cps) and 15,000 cps at roomtemperature, or more specifically between about 8,000 centipoise (cps)and 12,000 cps at room temperature, or more specifically between about9,000 centipoise (cps) and 11,000 cps at room temperature. For anotherexample, a diode ink for screen printing in which the diodes 100-100Lhave a GaN substrate 105 may have a viscosity between about 10,000centipoise (cps) and 25,000 cps at room temperature, or morespecifically between about 15,000 centipoise (cps) and 22,000 cps atroom temperature, or more specifically between about 17,500 centipoise(cps) and 20,500 cps at room temperature, or more specifically betweenabout 18,000 centipoise (cps) and 20,000 cps at room temperature. Alsofor example, a diode ink for flexographic printing in which the diodes100-100L have a silicon substrate 105 may have a viscosity between about1,000 centipoise (cps) and 10,000 cps at room temperature, or morespecifically between about 1,500 centipoise (cps) and 4,000 cps at roomtemperature, or more specifically between about 1,700 centipoise (cps)and 3,000 cps at room temperature, or more specifically between about1,800 centipoise (cps) and 2,200 cps at room temperature. Also forexample, a diode ink for flexographic printing in which the diodes100-100L have a GaN substrate 105 may have a viscosity between about1,000 centipoise (cps) and 10,000 cps at room temperature, or morespecifically between about 2,000 centipoise (cps) and 6,000 cps at roomtemperature, or more specifically between about 2,500 centipoise (cps)and 4,500 cps at room temperature, or more specifically between about2,000 centipoise (cps) and 4,000 cps at room temperature.

Viscosity may be measured in a wide variety of ways. For purposes ofcomparison, the various specified and/or claimed ranges of viscosityherein have been measured using a Brookfield viscometer (available fromBrookfield Engineering Laboratories of Middleboro, Mass., USA) at ashear stress of about 200 pascals (or more generally between 190 and 210pascals), in a water jacket at about 25° C., using a spindle SC4-27 at aspeed of about 10 rpm (or more generally between 1 and 30 rpm,particularly for refrigerated fluids, for example and withoutlimitation).

One or more thickeners (as a viscosity modifier) may be used, forexample and without limitation: clays such as hectorite clays, garamiteclays, organo-modified clays; saccharides and polysaccharides such asguar gum, xanthan gum; celluloses and modified celluloses such ashydroxy methylcellulose, methylcellulose, ethyl cellulose, propylmethylcellulose, methoxy cellulose, methoxy methylcellulose, methoxypropyl methylcellulose, hydroxy propyl methylcellulose, carboxymethylcellulose, hydroxy ethylcellulose, ethyl hydroxylethylcellulose,cellulose ether, cellulose ethyl ether, chitosan; polymers such asacrylate and (meth)acrylate polymers and copolymers; glycols such asethylene glycols, diethylene glycol, polyethylene glycols, propyleneglycols, dipropylene glycols, glycol ethers, glycol ether acetates;fumed silica (such as Cabosil), silica powders and modified ureas suchas BYK® 420 (available from BYK Chemie GmbH); and mixtures thereof.Other viscosity modifiers may be used, as well as particle addition tocontrol viscosity, as described in Lewis et al., Patent ApplicationPublication Pub. No. US 2003/0091647. Other viscosity modifiersdiscussed below with reference to dielectric inks may also be utilized,including without limitation polyvinyl pyrrolidone, polyethylene glycol,polyvinyl acetate (PVA), polyvinyl alcohols, polyacrylic acids,polyethylene oxides, polyvinyl butyral (PVB); diethylene glycol,propylene glycol, 2-ethyl oxazoline.

Referring to Diode Ink Example 6, the liquid suspension of diodes(100-100L) may further comprise an adhesive viscosity modifier, namely,any of the viscosity modifiers mentioned above which have the additionalproperty of adhesion. Such an adhesive viscosity modifier provides forboth adhering the diodes (100-100L) to a first conductor (e.g., 310A) orto a base 305, 305A during apparatus (300, 300A, 300B, 300C, 300D, 700,700A, 700B, 720, 730, 740, 750, 760, 770) fabrication (e.g., printing),and then further provides for an infrastructure (e.g., polymeric) (whendried or cured) for holding the diodes (100-100L) in place in anapparatus (300, 300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740,750, 760, 770). While providing such adhesion, such a viscosity modifiershould also have some capability to de-wet from the contacts of thediodes (100-100L), such as the terminals 125 and/or 127. Such adhesive,viscosity and de-wetting properties are among the reasonsmethylcellulose, methoxy propyl methylcellulose, or hydroxy propylmethylcellulose resins have been utilized in various exemplaryembodiments. Other suitable viscosity modifiers may also be selectedempirically.

Additional properties of the viscosity modifier or adhesive viscositymodifier are also useful and within the scope of the disclosure. First,such a viscosity modifier should prevent the suspended diodes (100-100L)from settling out at a selected temperature. Second, such a viscositymodifier should aid in orienting the diodes (100-100L) and printing thediodes (100-100L) in a uniform manner during apparatus (300, 300A, 300B,300C, 300D, 700, 700A, 700B, 720, 730, 740, 750, 760, 770) fabrication.Third, in some embodiments, the viscosity modifier should also serve tocushion or otherwise protect the diodes (100-100L) during the printingprocess, while in other embodiments, otherwise inert particles such asglass beads are added which serve to protect the diodes 100-100L duringthe printing process (Diode Ink Examples 17-19, discussed below).

Referring to Diode Ink Examples 3, 4 and 8, the liquid suspension ofdiodes (100-100L) may further comprise a second solvent (Example 8) or asolvating agent (Example 3) or a wetting solvent (Example 4), with manyexamples discussed in greater detail below. Such a (first or second)solvent is selected as a wetting (equivalently, solvating) or rewettingagent for facilitating ohmic contact between a first conductor (e.g.,310A, which may be comprised of a conductive polymer such as a silverink, a carbon ink, or mixture of silver and carbon ink) and the diodes100-100L (through the substrate 105, a through via structures (131, 133,134), and/or a second, back side metal layer 122, as illustrated in FIG.83), following printing and drying of the diode ink during subsequentdevice manufacture, such as a nonpolar resin solvent, including one ormore dibasic esters, also for example and without limitation. Forexample, when the diode ink is printed over a first conductor 310, thewetting or solvating agent partially dissolves the first conductor 310;as the wetting or solvating agent subsequently dissipates, the firstconductor 310 re-hardens and forms a contact with the diodes (100-100L).

The balance of the liquid or gel suspension of diodes (100-100L) isgenerally another, third solvent, such as deionized water, and anydescriptions of percentages herein may assume that the balance of theliquid or gel suspension of diodes (100-100L) is such a third solventsuch as water, and all described percentages are based on weight, ratherthan volume or some other measure. It should also be noted that thevarious diode ink suspensions may all be mixed in a typical atmosphericsetting, without requiring any particular composition of air or othercontained or filtered environment.

Solvent selection may also be based upon the polarity of the solvent. Inan exemplary embodiment, a first solvent such as an alcohol may beselected as a polar or hydrophilic solvent, to facilitate de-wetting offof the diodes (100-100L) and other conductors (e.g., 310) duringapparatus 300, 300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740,750, 760, 770 fabrication, while concomitantly being able to be solublein or solubilize a viscosity modifier.

Another useful property of an exemplary diode ink is illustrated byExample 7. For this exemplary embodiment, the diode ink may be opaquewhen wet during printing, to aid in various printing processes such asregistration. When dried or cured, however, the dried or cured diode inkis substantially optically transmissive or otherwise clear at selectedwavelengths, such as to substantially not interfere with the emission ofvisible light generated by the diodes (100-100L). In other exemplaryembodiments, however, the diode ink may also be substantially opticallytransmissive or clear.

Another way to characterize an exemplary diode ink is based upon thesize of the diodes (100-100L), as illustrated by Example 9, in which thediodes 100-100L are generally less than about 450 microns in anydimension, and more specifically less than about 200 microns in anydimension, and more specifically less than about 100 microns in anydimension, and more specifically less than 50 microns in any dimension,and more specifically less than 30 microns in any dimension. In theillustrated exemplary embodiments, the diodes 100-100L are generally onthe order of about 10 to 50 microns in width, or more specifically about20 to 30 microns in width, and about 5 to 25 microns in height, or fromabout 25 to 28 microns in diameter (measured side face to face ratherthan apex to apex) and 8 to 15 microns in height or 9 to 12 microns inheight. In some exemplary embodiments, the height of the diodes 100-100Lexcluding the metal layer 120B forming the bump or protruding structure(i.e., the height of the lateral sides 121 including the GaNheterostructure) is on the order of about 5 to 15 microns, or morespecifically 7 to 12 microns, or more specifically 8 to 11 microns, ormore specifically 9 to 10 microns, or more specifically less than 10 to30 microns, while the height of the metal layer 120B forming the bump orprotruding structure is generally on the order of about 3 to 7 microns.

In other exemplary embodiments, the height of the diodes (e.g. 100L)excluding the metal layer 120B forming the bump or protruding structureand the back side metal 122 (i.e., the height of the lateral sides 121including the GaN heterostructure) is on the order of about less thanabout 10 microns, or more specifically less than about 8 microns, ormore specifically between about 2 to 6 microns, or more specificallybetween about 3 to 5 microns, or more specifically about 4.5 microns,while the height of the metal layer 120B forming the bump or protrudingstructure is generally on the order of between about 3 to 7 microns, ormore specifically on the order of between about 5 to 7 microns, whilethe overall height of the diodes 100L is on the order of about less thanabout 15 microns, or more specifically less than about 12 microns, ormore specifically between about 9 to 11 microns, or more specificallybetween about 10 to 11 microns, or more specifically about 10.5 microns.

In other exemplary embodiments, the height of the diodes (e.g. 100K)excluding the metal layer 120B and the back side metal 122 forming thebump or protruding structure (i.e., the height of the lateral sides 121including the GaN heterostructure) is on the order of about less thanabout 10 microns, or more specifically less than about 8 microns, ormore specifically between about 2 to 6 microns, or more specificallyabout 2 to 4 microns, or more specifically about 3.0 microns, while theheights of the metal layer 120B and back side metal 122 forming the bumpor protruding structure is generally on the order of between about 3 to7 microns, or more specifically on the order of between about 4 to 6microns, or more specifically about 5 microns, while the overall heightof the diodes 100K is on the order of about less than about 15 microns,or more specifically less than about 14 microns, or more specificallybetween about 12 to 14 microns, or more specifically about 13 microns.In other exemplary embodiments, the height of the diode 100K withoutincluding the height of the back side metal 122 forming the bump orprotruding structure but including the metal layer 120B is on the orderof about 5 to 10 microns.

The diode ink may also be characterized by its electrical properties, asillustrated in Example 10. In this exemplary embodiment, the diodes(100-100L) are suspended in at least one substantially non-insulatingcarrier or solvent, in contrast with an insulating binder, for example.

The diode ink may also be characterized by its surface properties, asillustrated in Example 11. In this exemplary embodiment, the diode inkhas a dewetting or contact angle greater than 25 degrees, or greaterthan 40 degrees, depending upon the surface energy of the substrateutilized for measurement, such as between 34 and 42 dynes, for example.

Diode Ink Example 12

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a first solvent comprising about 5% to 50% N-propanol, terpineol        or diethylene glycol, ethanol, tetrahydrofurfuryl alcohol,        and/or cyclohexanol, or mixtures thereof;    -   a viscosity modifier comprising about 0.75% to 5.0% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof;    -   a second solvent (or rewetting agent) comprising about 0.5% to        10% of a nonpolar resin solvent such as a dibasic ester; and    -   with the balance comprising a third solvent such as water.

Diode Ink Example 13

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a first solvent comprising about 15% to 40% N-propanol,        terpineol or diethylene glycol, ethanol, tetrahydrofurfuryl        alcohol, and/or cyclohexanol, or mixtures thereof;    -   a viscosity modifier comprising about 1.25% to 2.5% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof;    -   a second solvent (or rewetting agent) comprising about 0.5% to        10% of a nonpolar resin solvent such as a dibasic ester; and    -   with the balance comprising a third solvent such as water.

Diode Ink Example 14

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a first solvent comprising about 17.5% to 22.5% N-propanol,        terpineol or diethylene glycol, ethanol, tetrahydrofurfuryl        alcohol, and/or cyclohexanol or mixtures thereof;    -   a viscosity modifier comprising about 1.5% to 2.25% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof;    -   a second solvent (or rewetting agent) comprising between about        0.0% to 6.0% of at least one dibasic ester; and    -   with the balance comprising a third solvent such as water,        wherein the viscosity of the composition is substantially        between about 5,000 cps to about 20,000 cps at 25° C.

Diode Ink Example 15

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a first solvent comprising about 20% to 40% N-propanol,        terpineol or diethylene glycol, ethanol, tetrahydrofurfuryl        alcohol, and/or cyclohexanol, or mixtures thereof;    -   a viscosity modifier comprising about 1.25% to 1.75% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof;    -   a second solvent (or rewetting agent) comprising between about        0% to 6.0% of at least one dibasic ester; and    -   with the balance comprising a third solvent such as water,        wherein the viscosity of the composition is substantially        between about 1,000 cps to about 5,000 cps at 25° C.

Diode Ink Example 16

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a solvent; and    -   a viscosity modifier.

Diode Ink Example 17

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a solvent;    -   a viscosity modifier; and    -   at least one mechanical stabilizer or spacer.

Diode Ink Example 18

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a solvent;    -   a viscosity modifier; and    -   a plurality of inert particles having a range of sizes between        about 10 to 50 microns.

Diode Ink Example 19

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 20 to 30 microns and a height between        about 9 to 15 microns;    -   a solvent;    -   a viscosity modifier; and    -   a plurality of substantially optically transparent and        chemically inert particles having a range of sizes between about        15 to about 25 microns.

Diode Ink Example 20

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a first solvent comprising an alcohol;    -   a second solvent comprising a glycol;    -   a viscosity modifier comprising about 0.10% to 2.5% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof; and    -   a plurality of substantially optically transparent and        chemically inert particles having a range of sizes between about        10 to about 50 microns.

Diode Ink Example 21

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a mixture of at least a first solvent and a second solvent        different from the first solvent and comprising about 15% to        99.99% of at least two solvents selected from the group        consisting of: N-propanol, isopropanol, dipropylene glycol,        diethylene glycol, propylene glycol, 1-methoxy-2-propanol,        N-octanol, ethanol, tetrahydrofurfuryl alcohol, cyclohexanol,        and mixtures thereof; and    -   a viscosity modifier comprising about 0.10% to 2.5% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof.

Diode Ink Example 22

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a mixture of at least a first solvent and a second solvent        different from the first solvent and comprising about 15% to        99.99% of at least two solvents selected from the group        consisting of: N-propanol, isopropanol, dipropylene glycol,        diethylene glycol, propylene glycol, 1-methoxy-2-propanol,        N-octanol, ethanol, tetrahydrofurfuryl alcohol, cyclohexanol,        and mixtures thereof;    -   a viscosity modifier comprising about 0.10% to 2.5% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof;    -   about 0.01% to 2.5% of a plurality of substantially optically        transparent and chemically inert particles having a range of        sizes between about 10 to about 50 microns.

Diode Ink Example 23

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a mixture of at least a first solvent and a second solvent        different from the first solvent and comprising about 15% to        50.0% of at least two solvents selected from the group        consisting of: N-propanol, isopropanol, dipropylene glycol,        diethylene glycol, propylene glycol, 1-methoxy-2-propanol,        N-octanol, ethanol, tetrahydrofurfuryl alcohol, cyclohexanol,        and mixtures thereof;    -   a viscosity modifier comprising about 1.0% to 2.5% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof;    -   about 0.01% to 2.5% of a plurality of substantially optically        transparent and chemically inert particles having a range of        sizes between about 10 to about 50 microns; and    -   with the balance comprising a third solvent such as water.

Diode Ink Example 24

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a first solvent comprising about 15% to 40% of a solvent        selected from the group consisting of: N-propanol, isopropanol,        dipropylene glycol, diethylene glycol, propylene glycol,        1-methoxy-2-propanol, N-octanol, ethanol, tetrahydrofurfuryl        alcohol, cyclohexanol, and mixtures thereof;    -   a second solvent different from the first solvent and comprising        about 2% to 10% of a solvent selected from the group consisting        of: N-propanol, isopropanol, dipropylene glycol, diethylene        glycol, propylene glycol, 1-methoxy-2-propanol, N-octanol,        ethanol, tetrahydrofurfuryl alcohol, cyclohexanol, and mixtures        thereof;    -   a third solvent different from the first and second solvents and        comprising about 0.01% to 2.5% of a solvent selected from the        group consisting of: N-propanol, isopropanol, dipropylene        glycol, diethylene glycol, propylene glycol,        1-methoxy-2-propanol, N-octanol, ethanol, tetrahydrofurfuryl        alcohol, cyclohexanol, and mixtures thereof;    -   a viscosity modifier comprising about 1.0% to 2.5% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof; and    -   with the balance comprising a third solvent such as water.

Diode Ink Example 25

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a first solvent comprising about 15% to 30% of a solvent        selected from the group consisting of: N-propanol, isopropanol,        dipropylene glycol, diethylene glycol, propylene glycol,        1-methoxy-2-propanol, N-octanol, ethanol, tetrahydrofurfuryl        alcohol, cyclohexanol, and mixtures thereof;    -   a second solvent different from the first solvent and comprising        about 3% to 8% of a solvent selected from the group consisting        of: N-propanol, isopropanol, dipropylene glycol, diethylene        glycol, propylene glycol, 1-methoxy-2-propanol, N-octanol,        ethanol, tetrahydrofurfuryl alcohol, cyclohexanol, and mixtures        thereof;    -   a third solvent different from the first and second solvents and        comprising about 0.01% to 2.5% of a solvent selected from the        group consisting of: N-propanol, isopropanol, dipropylene        glycol, diethylene glycol, propylene glycol,        1-methoxy-2-propanol, N-octanol, ethanol, tetrahydrofurfuryl        alcohol, cyclohexanol, and mixtures thereof;    -   a viscosity modifier comprising about 1.25% to 2.5% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof;    -   about 0.01% to 2.5% of a plurality of substantially optically        transparent and chemically inert particles having a range of        sizes between about 10 to about 50 microns; and with the balance        comprising a third solvent such as water.

Diode Ink Example 26

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a first solvent comprising about 40% to 60% of a solvent        selected from the group consisting of: N-propanol, isopropanol,        dipropylene glycol, diethylene glycol, propylene glycol,        1-methoxy-2-propanol, N-octanol, ethanol, tetrahydrofurfuryl        alcohol, cyclohexanol, and mixtures thereof;    -   a second solvent different from the first solvent and comprising        about 40% to 60% of a solvent selected from the group consisting        of: N-propanol, isopropanol, dipropylene glycol, diethylene        glycol, propylene glycol, 1-methoxy-2-propanol, N-octanol,        ethanol, tetrahydrofurfuryl alcohol, cyclohexanol, and mixtures        thereof; and    -   a viscosity modifier comprising about 0.10% to 1.25% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof.

Diode Ink Example 27

-   -   A composition comprising:    -   a plurality of diodes 100-100L having a diameter (width and/or        length) between about 10 to 50 microns and a height between 5 to        25 microns;    -   a first solvent comprising about 40% to 60% of a solvent        selected from the group consisting of: N-propanol, isopropanol,        dipropylene glycol, diethylene glycol, propylene glycol,        1-methoxy-2-propanol, 1-octanol, ethanol, tetrahydrofurfuryl        alcohol, cyclohexanol, and mixtures thereof;    -   a second solvent different from the first solvent and comprising        about 40% to 60% of a solvent selected from the group consisting        of: N-propanol, isopropanol, dipropylene glycol, diethylene        glycol, propylene glycol, 1-methoxy-2-propanol, 1-octanol,        ethanol, tetrahydrofurfuryl alcohol, cyclohexanol, and mixtures        thereof;    -   a viscosity modifier comprising about 0.10% to 1.25% methoxy        propyl methylcellulose resin, or hydroxy propyl methylcellulose        resin, or other cellulose or methylcellulose resin, or mixtures        thereof; and    -   about 0.01% to 2.5% of a plurality of substantially optically        transparent and chemically inert particles having a range of        sizes between about 10 to 50 microns.

Referring to Diode Ink Examples 12-27, in an exemplary embodiment,another alcohol as the first solvent, N-propanol (“NPA”) (and/orN-octanol (e.g., 1-octanol (or any of various secondary or tertiaryoctanol isomers), 1-methoxy-2-propanol, terpineol, diethylene glycol,dipropylene glycol, tetrahydrofurfuryl alcohol, or cyclohexanol), issubstituted for substantially all or most of the IPA. With the diodes100-100L generally or mostly settled at the bottom of the container, IPAis removed, NPA is added, the mixture of IPA, NPA and diodes 100-100L isagitated or mixed at room temperature, followed by once again allowingthe diodes 100-100L to settle to the bottom of the container, andremoving a portion of the mixture of IPA and NPA, and adding more NPA(about 120-140 ml). This process of adding NPA and removing a mixture ofIPA and NPA, is generally repeated twice, resulting in a mixture ofpredominantly NPA, diodes 100-100L, trace or otherwise small amounts ofIPA, and potentially residual wafer adhesive and wafer adhesive solvent170, generally also in trace or otherwise small amounts. In an exemplaryembodiment, the residual or trace amounts of IPA remaining are less thanabout 1%, and more generally about 0.4%. Also in an exemplaryembodiment, the final percentage of NPA in an exemplary diode ink, ifany, is between about 0.5% to 50%, or more specifically about 1.0% to10%, or more specifically about 3% to 7%, or in other embodiments, morespecifically about 15% to 40%, or more specifically about 17.5% to22.5%, or more specifically about 25% to about 35%, depending upon thetype of printing to be utilized. When terpineol and/or diethylene glycolare utilized with or instead of NPA, a typical concentration ofterpineol is about 0.5% to 2.0%, and a typical concentration ofdiethylene glycol is about 15% to 25%. The IPA, NPA, rewetting agents,deionized water (and other compounds and mixtures utilized to formexemplary diode inks) may also be filtered to about 25 microns orsmaller to remove particle contaminants which are larger than or on thesame scale as the diodes 100-100L.

The mixture of substantially NPA or another first solvent and diodes100-100L is then added to and mixed or stirred briefly with a viscositymodifier, for example, such as a methoxy propyl methylcellulose resin,hydroxy propyl methylcellulose resin, or other cellulose ormethylcellulose resin. In an exemplary embodiment, E-3 and E-10methylcellulose resins available from The Dow Chemical Company(www.dow.com) and Hercules Chemical Company, Inc. (www.herchem.com) areutilized, resulting in a final percentage in an exemplary diode ink ofabout 0.10% to 5.0%, or more specifically about 0.2% to 1.25%, or morespecifically about 0.3% to 0.7%, or more specifically about 0.4% to0.6%, or more specifically about 1.25% to 2.5%, or more specifically1.5% to 2.0%, or more specifically less than or equal to 2.0%. In anexemplary embodiment, about a 3.0% E-10 formulation is utilized and isdiluted with deionized and filtered water to result in the finalpercentage in the completed composition. Other viscosity modifiers maybe utilized equivalently, including those discussed above and thosediscussed below with reference to dielectric inks. The viscositymodifier provides sufficient viscosity for the diodes 100-100L that theyare substantially dispersed and maintained in suspension and do notsettle out of the liquid or gel suspension, particularly underrefrigeration.

As mentioned above, a second solvent (or a first solvent for Examples 3and 4), generally a nonpolar resin solvent such as one or more dibasicesters, may then added. In an exemplary embodiment, a mixture of twodibasic esters is utilized to reach a final percentage of about 0.0% toabout 10%, or more specifically about 0.5% to about 6.0%, or morespecifically about 1.0% to about 5.0%, or more specifically about 2.0%to about 4.0%, or more specifically about 2.5% to about 3.5%, such asdimethyl glutarate or such as a mixture of about two thirds (⅔) dimethylglutarate and about one third (⅓) dimethyl succinate at a finalpercentage of about 3.73%, e.g., respectively using DBE-5 or DBE-9available from Invista USA of Wilmington, Del., USA, which also hastrace or otherwise small amounts of impurities such as about 0.2% ofdimethyl adipate and 0.04% water). A third solvent such as deionizedwater is also added, to adjust the relative percentages and reduceviscosity, as may be necessary or desirable. In addition to dibasicesters, other second solvents which may be utilized equivalentlyinclude, for example and without limitation, water; alcohols such asmethanol, ethanol, N-propanol (including 1-propanol, 2-propanol(isopropanol), 1-methoxy-2-propanol), isobutanol, butanol (including1-butanol, 2-butanol), pentanol (including 1-pentanol, 2-pentanol,3-pentanol), N-octanol (including 1-octanol, 2-octanol, 3-octanol),tetrahydrofurfuryl alcohol, cyclohexanol; ethers such as methyl ethylether, diethyl ether, ethyl propyl ether, and polyethers; esters suchethyl acetate, dimethyl adipate, propylene glycol monomethyl etheracetate (and dimethyl glutarate and dimethyl succinate as mentionedabove); glycols such as ethylene glycols, diethylene glycol,polyethylene glycols, propylene glycols, dipropylene glycols, glycolethers, glycol ether acetates; carbonates such as propylene carbonate;glycerols such as glycerin; acetonitrile, tetrahydrofuran (THF),dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide(DMSO); and mixtures thereof. In an exemplary embodiment, molar ratiosof the amount of first solvent to the amount of second solvent are inthe range of at least about 2 to 1, and more specifically in the rangeof at least about 5 to 1, and more specifically in the range of at leastabout 12 to 1 or higher; in other instances, the functionality of thetwo solvents may be combined into a single agent, with one polar ornonpolar solvent utilized in an exemplary embodiment. Also in additionto the dibasic esters discussed above, exemplary dissolving, wetting orsolvating agents, for example and without limitation, also as mentionedbelow, include propylene glycol monomethyl ether acetate (C₆H₁₂O₃) (soldby Eastman under the name “PM Acetate”), used in an approximately 1:8molar ratio (or 22:78 by weight) with 1-propanol (or isopropanol) toform the suspending medium, and a variety of dibasic esters, andmixtures thereof, such as dimethyl succinate, dimethyl adipate anddimethyl glutarate (which are available in varying mixtures from Invistaunder the product names DBE, DBE-2, DBE-3, DBE-4, DBE-5, DBE-6, DBE-9and DBE-IB). In an exemplary embodiment, DBE-9 has been utilized. Themolar ratios of solvents will vary based upon the selected solvents,with 1:8 and 1:12 being typical ratios.

Referring to Diode Ink Examples 17-20, 22, 25 and 27, one or moremechanical stabilizers or spacers are included, such as chemically inertparticles and/or optically transparent particles, such as glass beadstypically comprised of a silicate or borosilicate glass, for example andwithout limitation. In various exemplary embodiments, about 0.01% to2.5%, or more particularly about 0.05% to 1.0%, or more particularlyabout 0.1% to 0.3% by weight of glass spheres or beads are utilized,having an average size or range of sizes between about 10 to 30 microns,or more particularly between about 12 to 28 microns, or moreparticularly between about 15 to 25 microns. These particles providemechanical stability and/or spacing during the printing process, such asacting as sheet spacers while printed sheets are fed into a printingpress, as the diodes 100-100L are initially held in place only through acomparatively thin film of dried or cured diode ink (illustrated inFIGS. 89 and 90). In general, the concentration of inert particles issufficiently low such that the number of inert particles per unit area(of the apparatus area, following deposition) is less than the densityof diodes 100-100L per unit area. The inert particles provide mechanicalstability and spacing, tending to prevent diodes 100-100L from beingdislodged and lost when printed sheets are slid over one another as theyare fed into a printing press when either a conductive layer (310)and/or a dielectric layer (315) are being deposited, providing stabilityanalogously to ball bearings. Following deposition of a conductive layer(310) and/or a dielectric layer (315), the diodes 100-100L areeffectively held or locked in place, with a significantly diminishedlikelihood of being dislodged. The inert particles are also held orlocked in place, but perform no further function in a completedapparatus 300, 700, 720, 730, 740, 750, 760, 770 and are effectivelyelectrically and chemically inert. A plurality of inert particles 292are illustrated in cross-section in FIG. 94, and although not separatelyillustrated in the other Figures, may be included in any of the otherillustrated apparatuses.

Diode Ink Examples 20-27 are illustrated to provide additional and morespecific examples of diode ink compositions which have been effectivefor fabrication of various apparatus 300, 700, 720, 730, 740, 750, 760,770 embodiments. Diode Ink Example 20 and other Examples havingcellulose or methylcellulose resins such as hydroxy propylmethylcellulose resin may also include additional solvents not mentionedseparately, such as water or 1-methoxy-2-propanol, for example andwithout limitation.

While generally the various diode inks are mixed in the order describedabove, it should also be noted that the various first solvent, viscositymodifier, second solvent, and third solvent (such as water) may be addedor mixed together in other orders, any and all of which are within thescope of the disclosure. For example, deionized water (as a thirdsolvent) may be added first, followed by 1-propanol and DBE-9, followedby a viscosity modifier, and then followed by additional water, as maybe needed, to adjust relative percentages and viscosity, also forexample.

The mixture of substantially a first solvent such as NPA, diodes100-100L, a viscosity modifier, a second solvent, and a third solvent(if any) such as water are then mixed or agitated, such as by using animpeller mixer, at a comparatively low speed to avoid incorporating airinto the mixture, for about 25-30 minutes at room temperature in an airatmosphere. In an exemplary embodiment, the resulting volume of diodeink is typically on the order of about one-half to one liter (per wafer)containing 9-10 million diodes 100-100L, and the concentration of diodes100-100L may be adjusted up or down as desired, such as depending uponthe concentration desired for a selected printed LED or photovoltaicdevice, described below, with exemplary viscosity ranges described abovefor different types of printing and different types of diodes 100-100L.A first solvent such as NPA also tends to act as a preservative andinhibits bacterial and fungal growth for storage of the resulting diodeink. When other first solvents are to be utilized, a separatepreserving, inhibiting or fungicidal agent may also be added. For anexemplary embodiment, additional surfactants or non-foaming agents forprinting may be utilized as an option, but are not required for properfunctioning and exemplary printing.

The concentration of diodes 100-100L may be adjusted according to theapparatus requirements. For example, for lighting applications, a lowersurface brightness lamp may utilize about 25 diodes 100-100L per squarecm, using a diode ink having a concentration of diodes 100-100L of about12,500 diodes per ml (cm³). For another exemplary embodiment, one wafer150 may contain about 7.2 million diodes 100-100L, for about 570 ml ofdiode ink. Each milliliter of diode ink may be used to cover about 500square centimeters when printed, with 570 ml of diode ink covering about28.8 square meters. Also for example, for a very high surface brightnesslamp, using about 100 diodes 100-100L per square cm, would require aconcentration of diodes 100-100L of about 50,000 per ml (cm³).

FIG. 75 is a flow diagram illustrating an exemplary method embodimentfor manufacturing diode ink, and provides a useful summary. The methodbegins, start step 200, with releasing the diodes 100-100L from thewafer 150, 150A, step 205. As discussed above, this step involvesattaching the wafer on a first, diode side to a wafer holder with awafer bond adhesive, using laser lift-off, grinding and/or polishingand/or etching of the second, back side of the wafer to reveal thesingulation trenches and remove any additional substrate or GaN asdesired or specified, and dissolving the wafer bond adhesive to releasethe diodes 100-100L into a solvent such as IPA or into another solventsuch as NPA or any of the other solvents described herein. When IPA isutilized, the method includes optional step 210, of transferring thediodes 100-100L to a (first) solvent such as NPA. The method then addsthe diodes 100-100L in the first solvent to a viscosity modifier such asmethylcellulose, step 215, and adds one or more second solvents, such asone or two dibasic esters, such as dimethyl glutarate and/or dimethylsuccinate, step 220. Any weight percentages may be adjusted using athird solvent such as deionized water, step 225. In step 230, the methodthen mixes the plurality of diodes 100-100L, first solvent, viscositymodifier, second solvent (and a plurality of chemically and electricallyinert particles, such as glass beads) and any additional deionized waterfor about 25-30 minutes at room temperature (about 25° C.) in an airatmosphere, with a resulting viscosity between about 1,000 cps to about25,000 cps. The method may then end, return step 235. It should also benoted that steps 215, 220, and 225 may occur in other orders, asdescribed above, and may be repeated as needed, and that optional,additional mixing steps may also be utilized.

FIG. 76 is a perspective view of an exemplary apparatus 300 embodiment.FIG. 77 is a plan (or top) view illustrating an exemplary electrodestructure of a first conductive layer for an exemplary apparatusembodiment. FIG. 78 is a first cross-sectional view (through the 30-30′plane of FIG. 76) of an exemplary apparatus 300 embodiment. FIG. 79 is asecond cross-sectional view (through the 31-31′ plane of FIG. 76) of anexemplary apparatus 300 embodiment. FIG. 80 is a perspective view of anexemplary second apparatus 700 embodiment. FIG. 81 is a firstcross-sectional view (through the 88-88′ plane of FIG. 80) of anexemplary second apparatus 700 embodiment. FIG. 82 is a secondcross-sectional view (through the 87-87′ plane of FIG. 80) of anexemplary second apparatus 700 embodiment. FIG. 83 is a secondcross-sectional view of exemplary diodes 100J, 100K, 100D and 100Ecoupled to a first conductor 310A. FIG. 87 is a cross-sectional view ofan exemplary third apparatus 300C embodiment to provide light emissionfrom two sides. FIG. 88 is a cross-sectional view of an exemplary fourthapparatus 300D embodiment to provide light emission from two sides. FIG.89 is a partial cross-sectional view in greater detail of an exemplaryfirst apparatus embodiment. FIG. 90 is a partial cross-sectional view ingreater detail of an exemplary second apparatus embodiment. FIG. 91 is aperspective view of an exemplary fifth apparatus 720 embodiment. FIG. 92is a cross-sectional view (through the 57-57′ plane of FIG. 91) of anexemplary fifth apparatus 720 embodiment. FIG. 93 is a perspective viewof an exemplary sixth apparatus 730 embodiment. FIG. 94 is across-sectional view (through the 58-58′ plane of FIG. 93) of anexemplary sixth apparatus 730 embodiment. FIG. 95 is a perspective viewof an exemplary seventh apparatus 740 embodiment. FIG. 96 is across-sectional view (through the 59-59′ plane of FIG. 95) of anexemplary seventh apparatus 740 embodiment. FIG. 97 is a perspectiveview of an exemplary eighth apparatus 750 embodiment. FIG. 98 is across-sectional view (through the 61-61′ plane of FIG. 97) of anexemplary eighth apparatus 750 embodiment. FIG. 99 is a plan (or top)view illustrating an exemplary second electrode structure of a firstconductive layer for an exemplary apparatus embodiment. FIG. 101 is aplan (or top) view of exemplary ninth and tenth apparatus 760, 770embodiments, typically utilized with the system 800, 810 embodimentsillustrated in FIG. 100. FIG. 102 is a cross-sectional view (through the63-63′ plane of FIG. 101) of an exemplary ninth apparatus 760embodiment. FIG. 103 is a cross-sectional view (through the 63-63′ planeof FIG. 101) of an exemplary tenth apparatus 770 embodiment. FIG. 109 isa photograph of an energized exemplary apparatus 300A embodimentemitting light.

Referring to FIGS. 76-79, in an apparatus 300, one or more firstconductors 310 are deposited on a base 305 on a first side, followed bydepositing a plurality of diodes 100-100K (coupling the second terminals127 to the conductors 310), a dielectric layer 315, second conductor(s)320 (generally transparent conductors coupling to the first terminals),optionally followed by a stabilization layer 335, luminescent (oremissive) layer 325, and protective layer or coating 330. In thisapparatus 300 embodiment, if an optically opaque base 305 and firstconductor(s) 310 are utilized, light is emitted or absorbed primarilythrough the top, first side of the apparatus 300, and if an opticallytransmissive base 305 and first conductor(s) 310 are utilized, light isemitted or absorbed form or to both sides of the apparatus 300,particularly if energized with an AC voltage to energize diodes 100-100Khaving either a first or second orientation.

Referring to FIGS. 80-83, in an apparatus 700, a plurality of diodes100L are deposited on a first side of an base 305 which is opticallytransmissive and therefore referred to herein as a base 305A, followedby depositing one or more first conductors 310 (coupling the conductors310 to the second terminals 127), a dielectric layer 315, secondconductor(s) 320 (coupling to the first terminals) (which may or may notbe optically transmissive), and optionally followed by a stabilizationlayer 335 and protective layer or coating 330. An optional luminescent(or emissive) layer 325 may be applied to the second side of the base305, along with any other protective layer or coating 330, either beforeor after any of the deposition steps on the first side of the base 305.In this apparatus 700 embodiment, if one or more optically opaque secondconductors 320 are utilized, light is emitted or absorbed primarilythrough the base 305A of the apparatus 700 on the second side, and ifone or more optically transmissive second conductors 320 are utilized,light is emitted or absorbed on both sides of the apparatus 700.

The various apparatus 300, 700, 720, 730, 740, 750, 760, 770 embodimentsmay be printed as flexible sheets of LED-based lighting or otherluminaires, for example, which may be curled, folded, twisted, spiraled,flattened, knotted, creased, and otherwise shaped into any of variousforms and designs, of any kind, including architectural shapes, foldedand creased origami shapes of other artistic or fanciful designs, Edisonbulb shapes, fluorescent bulb shapes, chandelier shapes, for example andwithout limitation, with one such curled and folded Edison bulb shapeillustrated in FIG. 100 as system 800, 810. The various apparatus 300,700 embodiments may also be combined in various ways, such asback-to-back, to have light emitted or absorbed from both sides of theresulting device. For example and without limitation, two apparatuses300 may be combined back-to-back on the second sides of the respectivesubstrates 305 to form an apparatus 300C embodiment, or an apparatus 300may be printed on both sides of a substrate 305 to form an apparatus300D embodiment, both as illustrated in cross-section in FIGS. 87 and88, respectively. Also for example and without limitation, notseparately illustrated, two apparatuses 700 also may be combinedback-to-back on the non-substrate 305, first side, also providing lightemission from both sides of the resulting device.

Referring to FIGS. 91-92, in an apparatus 720, a first conductor 310 isdeposited as one or more layers on a base 305 on a first side, followedby depositing a carbon contact 322A to couple to the conductor 310,followed by depositing a plurality of diodes 100-100K (coupling thesecond terminals 127 to the conductors 310), a dielectric layer 315, asecond conductor 320 also deposited as one or more layers (generallytransparent conductors coupling to the first terminals), followed bydepositing a carbon contact 322B to couple to the conductor 320,optionally followed by a stabilization layer 335, luminescent (oremissive) layer 325, and protective layer or coating 330. In thisapparatus 300 embodiment, light is emitted or absorbed primarily throughthe top, first side of the apparatus 720, and if an opticallytransmissive base 305 and first conductors 310 are utilized, light isemitted or absorbed form or to both sides of the apparatus 720,particularly if energized with an AC voltage.

Referring to FIGS. 93-94, in an apparatus 730, a substantially opticallytransmissive first conductor 310 is deposited as one or more layers onan optically transmissive base 305A on a first side, followed bydepositing a carbon contact 322A to couple to the conductor 310,followed by depositing a plurality of diodes 100-100K (coupling thesecond terminals 127 to the conductors 310) with a plurality of inertparticles 292, a dielectric layer 315, a second conductor 320 alsodeposited as one or more layers (also generally transparent conductorscoupling to the first terminals), followed by depositing a carboncontact 322B to couple to the conductor 320, optionally followed by astabilization layer 335, a first luminescent (or emissive) layer 325,and protective layer or coating 330, followed by depositing on thesecond side of the base 305A a second luminescent (or emissive) layer325, and protective layer or coating 330. In this apparatus 730embodiment, light is emitted or absorbed through both the top, firstside and the bottom, second side of the apparatus 730. In addition, theuse of the second luminescent (or emissive) layer 325 may also shift thewavelengths of the light emitted through the second side (in addition tothe first luminescent (or emissive) layer 325 shifting the spectrum ofthe light emitted through on the first side).

Referring to FIGS. 95-96, in an apparatus 740, a plurality of diodes100L are deposited on a first side of an base 305 which is opticallytransmissive and also referred to herein as a base 305A, followed bydepositing a first conductor 310 as one or more layers (coupling theconductor 310 to the second terminals 127), followed by depositing acarbon contact 322A to couple to the conductor 310, a dielectric layer315, a second conductor 320 also deposited as one or more layers(coupling to the first terminals), followed by depositing a carboncontact 322B to couple to the conductor 320, and optionally followed bya stabilization layer 335 and protective layer or coating 330. Anoptional luminescent (or emissive) layer 325 may be applied to thesecond side of the base 305, along with any other protective layer orcoating 330, either before or after any of the deposition steps on thefirst side of the base 305. In this apparatus 740 embodiment, light isemitted or absorbed primarily through the base 305A of the apparatus 740on the second side (also with any shift of wavelengths from the firstluminescent (or emissive) layer 325), and if one or more opticallytransmissive second conductors 320 are utilized, light is emitted orabsorbed on both sides of the apparatus 740.

Referring to FIGS. 97-98, in an apparatus 750, a plurality of diodes100L are deposited on a first side of an base 305 which is opticallytransmissive and also referred to herein as a base 305A, followed bydepositing a first conductor 310 as one or more layers (coupling theconductor 310 to the second terminals 127), followed by depositing acarbon contact 322A to couple to the conductor 310, a dielectric layer315, a substantially optically transmissive second conductor 320 alsodeposited as one or more layers (coupling to the first terminals),followed by depositing a carbon contact 322B to couple to the conductor320, and optionally followed by a stabilization layer 335, an optionalfirst luminescent (or emissive) layer 325, and protective layer orcoating 330. An optional second luminescent (or emissive) layer 325 maybe applied to the second side of the base 305A, along with any otherprotective layer or coating 330, either before or after any of thedeposition steps on the first side of the base 305. In this apparatus750 embodiment, light is emitted or absorbed through both the top, firstside and the bottom, second side of the apparatus 750, also with anyshift of wavelengths from the first and second luminescent (or emissive)layers 325.

Apparatuses 760 and 770 will be described in greater detail below withreference to FIGS. 100-103, and differ from the other illustratedapparatuses in utilizing a third conductor 312, also typically depositedas one or more layers. In addition, apparatus 770 also illustrates useof a barrier layer 318, discussed in greater detail below.

As mentioned above, the apparatus 300, 700, 720, 730, 740, 750, 760, 770is formed by depositing (e.g., printing) a plurality of layers on a base305, namely, for an apparatus 300, 720, 730, 750, depositing one or morefirst conductors 310 on the base 305, either as a layer or a pluralityof conductors 310, followed by depositing the diodes 100-100L while inthe liquid or gel suspension (to a wet film thickness of about 18 to 20or more microns) (i.e., a diode ink), and evaporating or otherwisedispersing the liquid/gel portion of the suspension, and for anapparatus 700, 740, 750, by depositing the diodes 100-100L while in theliquid or gel suspension (to a wet film thickness of about 18 to 20 ormore microns) (i.e., a diode ink) over a first side of the opticallytransmissive base 305A and evaporating or otherwise dispersing theliquid/gel portion of the suspension, followed by depositing one or morefirst conductors 310.

As the liquid or gel suspension of diodes 100-100L dries or cures, thecomponents of the diode ink (especially the viscosity modifier oradhesive viscosity modifier, as mentioned above) form a comparativelythin film, coating, lattice or mesh around the diodes 100-100L, helpingto hold them in place on the base 305 or first conductor(s) 310,illustrated as film 295 in FIGS. 89 and 90, typically on the order ofabout 50 nm to about 300 nm thick (when fully cured or dried), dependingupon the concentration of viscosity modifier utilized, such as about50-100 nm for lower concentrations of viscosity modifier, and about200-300 nm for higher concentrations of viscosity modifier. Thedeposited film 295 may be continuous, surrounding the diodes 100-100L,as illustrated in FIG. 89, or may be discontinuous, leaving gaps andonly partially surrounding the diodes 100-100L, as illustrated in FIG.90. While the terminals 125, 127 are typically coated with the diode inkfilm 295, there is generally sufficient surface roughness of theterminals 125, 127 that the film 295 does not interfere with makingelectrical connections to the first and second conductors 310, 320. Thefilm 295 typically comprises a cured or dried form of the viscositymodifier, and potentially also small or trace amounts of the varioussolvents, such as the first or second solvents, as mentioned below withreference to cured or dried diode ink embodiments. Also as discussed ingreater detail below, a viscosity modifier may also be utilized to forma barrier layer 318, discussed below with reference to FIG. 103.

For an apparatus 300, the diodes 100-100K are physically andelectrically coupled to the one or more first conductors 310A, and foran apparatus 700, the diodes 100K are physically coupled to the base 305and subsequently coupled to the one or more first conductors 310, and inboth apparatus 300, 700 embodiments, because of having been depositedwhile suspended in any orientation in a liquid or gel, the diodes100-100L may be in a first orientation (first terminal 125 in an updirection), in a second orientation (first terminal 125 in a downdirection), or possibly in a third orientation (first terminal 125 issideways). In addition, because of having been deposited while suspendedin a liquid or gel, the diodes 100-100L are generally spaced quiteirregularly within an apparatus 300, 700. In addition, as mentionedabove, in exemplary embodiments, the diode ink may include a pluralityof chemically inert, typically optically transmissive particles, such asglass beads, having a range of sizes between about 10 to 30 microns, ormore particularly between about 12 to 28 microns, or more particularlybetween about 15 to 25 microns.

In the first, up orientation or direction, as illustrated in FIG. 83,the first terminal 125 (either metal layer 120B forming the bump orprotruding structure for diodes 100-100J or the metal layer 122 of diode100K) is oriented upward, and the diodes 100-100K are coupled to the oneor more first conductors 310A through second terminal 127, which may bea metal layer 120B for a diode 100K, or a back side metal layer 122 asillustrated for diode 100J, or through a center via 131 as illustratedfor diode 100D (embodied without the optional back side metal layer 122of a diode 100J), or through a peripheral via 134 (not separatelyillustrated), or through substrate 105 as illustrated for diode 100E. Inthe second, down orientation or direction, illustrated in FIGS. 78 and79, the first terminal 125 is oriented downward, and the diodes 100-100Kare or may be coupled to the one or more first conductors 310A throughthe first terminal 125 (e.g., either metal layer 120B forming the bumpor protruding structure for diodes 100-100J or the metal layer 122 ofdiode 100K).

For a diode 100L, the diode 100L may be oriented in a first, uporientation or direction illustrated in FIGS. 81 and 82, in which bothfirst and second terminals 125, 127 are oriented upward, and notseparately illustrated, may be oriented in a second, down orientation ordirection, in which both first and second terminals 125, 127 areoriented downward. For such a downward orientation, it should be notedthat while the first terminal 125 may be in electrical contact with theone or more first conductors 310, the second terminal 127 is more likelyto be within the dielectric layer 135 and will not make contact with asecond conductor 320, resulting in that diode 100L being electricallyisolated and nonfunctional when having the second orientation, which maybe desirable in many embodiments.

Insofar as the diodes 100-100L are being deposited while suspended in aliquid or gel with indeterminate spacing between them and in any 360degrees of orientation, it is not known in advance with any certainty(e.g., within a non-defect rate of 4-6 sigma of the mean for most highquality manufacturing) precisely where and in what orientation anyparticular diode 100-100L will land on the substrate 305A or one or morefirst conductors 310. Rather, there will be statistical distributionsfor both spacing of the diodes 100-100L from each other and theorientation of the diodes 100-100L (first, up or second, down). What canbe said with a high degree of certainty is that of the potentiallymillions of diodes 100-100L which may be deposited on a substrate 305,305A sheet or series of sheets, at least one such diode 100-100L willend up in a second orientation, because of having been deposited whiledispersed and suspended in a liquid or gel.

Accordingly, the distribution and orientation of diodes 100-100L in anapparatus 300, 700, 720, 730, 740, 750, 760, 770 may be describedstatistically. For example, while it may be unknown or indeterminate inadvance of deposition precisely where and in what orientation anyparticular diode 100-100L will land and be held in place on thesubstrate 305A or one or more first conductors 310, on average a certainnumber of diodes 100-100L will be in a particular orientation in acertain concentration of diodes 100-100L per unit area, such as 25diodes 100-100L per square centimeter, for example and withoutlimitation.

Accordingly, the diodes 100-100L may be considered to be or have beendeposited in an effectively random or pseudo-random orientation and withirregular spacing, and may be up in a first orientation (first terminal125 up), which is typically the direction of a forward bias voltage fordiodes 100-100J and a reverse bias for diodes 100K (depending upon thepolarity of the applied voltage), or down in a second orientation (firstterminal 125 down), which is typically the direction of a reverse biasvoltage for diodes 100-100J and forward bias for diodes 100K, (alsodepending upon the polarity of the applied voltage). Similarly fordiodes 100L, which may be up in a first orientation (first and secondterminals 125, 127 up), which is typically the direction of a forwardbias voltage for diodes 100L, or down in a second orientation (first andsecond terminals 125, 127 down), which is typically the direction of areverse bias voltage for diodes 100L (also depending upon the polarityof the applied voltage), although as mentioned above and as described ingreater detail below, diodes 100L which are in the second orientationare typically not fully coupled electrically and are non-functioning. Itis also possible that diodes 100-100L are deposited or end up sidewaysin a third orientation (a diode lateral side 121 down and another diodelateral side 121 up).

Fluid dynamics, the viscosity or rheology of the diode ink, screen meshcount, screen mesh openings, screen mesh material (surface energy of thescreen mesh material), print speed, orientation of the tines of theinterdigitated or comb structure of the first conductors 310 (tinesbeing perpendicular to the direction of the motion of the base 305through a printing press), the surface energy of the base 305 or firstconductor(s) 310 upon which the diodes 100-100L are deposited, the shapeand size of the diodes 100-100L, the printed or deposited density of thediodes 100-100L, the shape, size and/or thickness of the diode lateralsides 121, and sonication or other mechanical vibration of the liquid orgel suspension of diodes 100-100L prior to curing or drying of the diodeink, appear to influence the predominance of one first, second or thirdorientation over another first, second or third orientation. Forexample, diode lateral sides 121 being less than about 10 microns inheight (or the vertical thickness, with vertical being with reference tothe first or second orientations), and more particularly less than about8 microns in height, such that the diodes 100-100L have comparativelythin sides or edges, significantly decreases the percentage of diodes100-100L having the third orientation.

Similarly, fluid dynamics, higher viscosities, and lower mesh count andthe other factors mentioned above provide a degree of control over theorientation of the diodes 100-100L, allowing the percentages of diodes100-100L in the first or second orientations to be tuned or adjusted fora given application. For example, the factors enumerated above may beadjusted to increase the prevalence of the first orientation, resultingin a first orientation of as many as 80% to 90% of the diodes 100-100Lor more. Also for example, the factors enumerated above may be adjustedto balance the prevalence of the first and second orientations,resulting in an approximately or substantially equal distribution of thefirst orientation and the second orientation of the diodes 100-100L,e.g., 40% to 60% of the diodes 100-100L in the first orientation and 60%to 40% of the diodes 100-100L in the second orientation.

It should be noted that even with a significantly high percentage ofdiodes 100-100L coupled to the first conductor 310A or base 305 in thefirst, up orientation or direction, statistically there is nonetheless asignificant probability that at least one or more diodes 100-100L willhave the second, down orientation or direction, and that statisticallythe diodes 100-100L will also exhibit irregular spacing, with somediodes 100-100J spaced comparatively closer, and at least some diodes100-100J spaced apart much more.

Stated another way, depending upon the polarity of the applied voltage,while a significantly high percentage of diodes 100-100L are or will becoupled in a first, forward bias orientation or direction, statisticallyat least one or more diodes 100-100L will have a second, reverse biasorientation or direction. In the event the light emitting or absorbingregion 140 is oriented differently, then those having skill in the artwill recognize that also depending upon the polarity of the appliedvoltage, the first orientation will be a reverse bias orientation, andthe second orientation will be a forward bias orientation.

For example, unlike traditional electronics manufacturing in whichelectrical components such as diodes are positioned for surfacemounting, within a selected tolerance level, onto a predeterminedlocation and in a predetermined orientation on a circuit board using apick and place machine, in any given instance, there are no suchpredetermined or certain locations (in an x-y plane) and orientations(z-axis) for diodes 100-100L in an apparatus 300, 700 (i.e., at leastone diode 100-100L will be in a second orientation in an apparatus 300,700).

This is a significant departure from existing apparatus structures, inwhich all such diodes (such as LEDs) have a single orientation withrespect to the voltage rails, namely, all having their correspondinganodes coupled to the higher voltage and their cathodes coupled to thelower voltage. As a result of the statistical orientation, dependingupon the percentages of diodes 100-100L having first or secondorientations, and depending upon various diode characteristics such astolerances for reverse bias, the diodes 100-100L may be energized usingeither an AC or a DC voltage or current, without additional switching ofvoltage or current.

Referring to FIGS. 77 and 99, a plurality of first conductors 310 may beutilized, forming at least two separate electrode structures,illustrated as an interdigitated or comb electrode structures of a first(first) conductor electrode or contact 310A and a second (first)conductor electrode or contact 310B. As illustrated in FIG. 77, theconductors 310A and 310B have the same widths, and are illustrated inFIGS. 76 and 78 as having different widths, with all such variationswithin the scope of the disclosure. For the exemplary apparatus 300embodiment, the diode ink or suspension (having the diodes 100-100K) isdeposited over the conductor 310A. A second, transparent conductor 320(optically transmissive, discussed below) is subsequently deposited(over a dielectric layer, as discussed below) to make separateelectrical contact with the conductor 310B, as illustrated in FIG. 78.Although not separately illustrated, as an option, the exemplaryapparatus 700 embodiment may also have these 310A, 310B electricalconnections: after the diode ink or suspension (having the diodes 100L)is deposited over the base 305A, one or more conductors 310A and 310B(as an interdigitated or comb structure) may be deposited, followed by adielectric layer 315 over the conductors 310A. A second conductor 320,which does not need to be optically transmissive, is subsequentlydeposited (over a dielectric layer 315, as discussed below), and alsomay have an interdigitated or comb structure) to make separateelectrical contact with the conductors 310B, as illustrated in FIG. 78for an apparatus 300. As illustrated in FIGS. 80-82 for the apparatus700, to illustrate another structural alternative, the second terminals127 are coupled to one or more first conductors 310, and the firstterminals 125 are coupled to one or more second conductors 320. FIGS. 81and 91-98 also illustrate another structural option, applicable to anyof the apparatus 300, 700, 720, 730, 740, 750, 760, 770 embodiments, inwhich carbon electrodes 322A and 322B are respectively coupled to thefirst conductors 310 and the second conductors 320, and extend out ofthe protective coating 330, to provide for electrical connections orcouplings to the apparatus 300, 700.

It should be noted that when the first conductors 310 have theinterdigitated or comb structure illustrated in FIG. 77, the secondconductor 320 may be energized using first conductor 310B. Theinterdigitated or comb structure of the first conductors provideselectrical current balancing, such that every current path through thefirst conductor 310A, diodes 100-100L, second conductor 320, and firstconductor 310B is substantially within a predetermined range. Thisserves to minimize the distance current must travel through the second,transparent conductor, thereby decreasing resistance and heatgeneration, and generally providing current to all or most of the diodes100-100L in parallel and within a predetermined range of current levels.

In addition, multiple interdigitated or comb structures for the firstconductors 310 may also be coupled in series, such as to produce anoverall device voltage having the desired multiple of diode 100-100Jforward voltages, such as up to typical household voltages, for exampleand without limitation. For example, as illustrated in FIG. 99, for afirst region 711 (with diodes 100-100L coupled in parallel), theconductors 310B may be coupled to or deposited as an integral layer withconductors 310A of a second region 712 (which also has its diodes100-100L coupled in parallel), and for the second region 712 (withdiodes 100-100L coupled in parallel), the conductors 310B may be coupledto or deposited as an integral layer with conductors 310A of a thirdregion 713 (which also has its diodes 100-100L coupled in parallel), andso on, so that the first, second and third regions (711, 712, 713) arecoupled in series, with each such region having diodes 100-100L coupledin parallel. This series connection is also utilized with the system800, 810 and apparatus 760, 770 embodiments illustrated in FIGS.100-103.

Also as illustrated in FIG. 99, energizing of any of the interdigitatedor comb electrode structures may be performed by applying a voltagelevel to a busbar 714, coupled to all of the respective tines (310A,310B). The busbar 714 is typically sized to have a comparatively lowsheet resistance or impedance.

For comparatively smaller regions or for other applications, such asgraphical arts, such current balancing and impedance matching (sheetresistance matching) structures are unnecessary, and simpler structuresof the first and second conductors 310, 320 may be utilized, such as thelayer structures illustrated in FIGS. 91-98, 102, 103. For example, suchlayered structures may be utilized when the sheet resistances of thefirst and second conductors 310, 320 is a comparatively or relativelysmall proportion of the overall resistance of the first and secondconductors 310, 320 in conjunction with the diodes 100-100L. Also asillustrated in FIGS. 102 and 103, a third conductive layer 312 may alsobe utilized, such as to provide parallel busbar connections along acomparatively long strip of apparatus 300, 700, 720, 730, 740, 750, 760,770.

One or more dielectric layers 315 are then deposited over the diodes100-100L, in a way which leaves exposed either or both the firstterminal 125 in the first orientation or the second, back side of thediode 100-100K (or the GaN heterostructure of a diode 100L) when in thesecond orientation, in an amount sufficient to provide electricalinsulation between the one or more first conductors 310 (coupled to thediodes 100-100L) and the one or more second conductors 320 which aredeposited over the one or more dielectric layers 315 and which makecorresponding physical and electrical contact with the first terminal125 or the second, back side of the diode 100-100K, depending on theorientation. For an apparatus 300, an optional luminescent (or emissive)layer 325 may then be deposited, followed by an optional stabilizationlayer 335 and/or any lensing, dispersion or sealing layer 330. Forexample, such an optional luminescent (or emissive) layer 325 maycomprise a stokes shifting phosphor layer to produce a lamp or otherapparatus emitting a desired color or other selected wavelength range orspectrum. These various layers, conductors and other deposited compoundsare discussed in greater detail below. For an apparatus 700, a lensing,dispersion or sealing layer 330 generally is deposited over the one ormore second conductors 320 on the first side, and the an optionalluminescent (or emissive) layer 325 may then be deposited over thesubstrate 305 on the second side, followed by an optional stabilizationlayer 335 and/or any lensing, dispersion or sealing layer 330. Dependingupon the locations of the first and second conductors 310, 320, carbonelectrodes 322A, 322B may be applied after deposition of thecorresponding first and second conductors or after any deposition of alensing, dispersion or sealing layer 330. These various layers,conductors and other deposited compounds are discussed in greater detailbelow.

A base 305 may be formed from or comprise any suitable material, such asplastic, paper, cardboard, or coated paper or cardboard, for example andwithout limitation. The base 305 may comprise any flexible materialhaving the strength to withstand the intended use conditions. In anexemplary embodiment, a base 305, 305A comprises a substantiallyoptically transmissive polyester or plastic sheet, such as a CT-5 orCT-7 five or seven mil polyester (Mylar) sheet treated for printreceptiveness and commercially available from MacDermid Autotype, Inc.of MacDermid, Inc. of Denver, Colo., USA, or a Coveme acid treatedMylar, for example. In another exemplary embodiment, a base 305comprises a polyimide film such as Kapton commercially available fromDuPont, Inc. of Wilmington Del., USA, also for example. Also in anexemplary embodiment, base 305 comprises a material having a dielectricconstant capable of or suitable for providing sufficient electricalinsulation for the excitation voltages which may be selected. A base 305may comprise, also for example, any one or more of the following: paper,coated paper, plastic coated paper, fiber paper, cardboard, posterpaper, poster board, books, magazines, newspapers, wooden boards,plywood, and other paper or wood-based products in any selected form;plastic or polymer materials in any selected form (sheets, film, boards,and so on); natural and synthetic rubber materials and products in anyselected form; natural and synthetic fabrics in any selected form,including polymeric nonwovens (carded, meltblown and spunbond nowovens);extruded polyolefinic films, including LDPE films; glass, ceramic, andother silicon or silica-derived materials and products, in any selectedform; concrete (cured), stone, and other building materials andproducts; or any other product, currently existing or created in thefuture. In a first exemplary embodiment, a base 305, 305A may beselected which provides a degree of electrical insulation (i.e., has adielectric constant or insulating properties sufficient to provideelectrical insulation of the one or more first conductors 310 depositedor applied on a first (front) side of the base 305, either electricalinsulation from each other or from other apparatus or system components.For example, while comparatively expensive choices, a glass sheet or asilicon wafer also could be utilized as a base 305. In other exemplaryembodiments, however, a plastic sheet or a plastic-coated paper productis utilized to form the base 305 such as the polyester mentioned aboveor patent stock and 100 lb. cover stock available from Sappi, Ltd., orsimilar coated papers from other paper manufacturers such as MitsubishiPaper Mills, Mead, and other paper products. In another exemplaryembodiment, an embossed plastic sheet or a plastic-coated paper producthaving a plurality of grooves, also available from Sappi, Ltd. isutilized, with the grooves utilized for forming the conductors 310. Inadditional exemplary embodiments, any type of base 305 may be utilized,including without limitation, those with additional sealing orencapsulating layers (such as plastic, lacquer and vinyl) deposited toone or more surfaces of the base 305. The base 305, 305A may alsocomprise laminates or other bondings of any of the foregoing materials.

In an exemplary embodiment, the comparatively small size of the diodes100-100L, spread out over a substrate 305, 305A, provides for acomparatively fast heat dissipation without requiring a heat sink, andthe availability of a wide range of materials suitable to be a base 305,305A, including those materials having a relatively low flash-ignitiontemperature. These temperatures may include at or above 50° C.,alternatively at or above 75° C., alternatively 100° C., or 125° C., or150° C., or 200° C., or 300° C., for example and without limitation, andmay be measured using the ISO 871:2006 standard, also for example andwithout limitation. The apparatus 300, 700 also generally has acomparatively lower operating temperature, for example, a mean operatingtemperature of less than about 150° C., or less than about 125° C., orless than about 100° C. or less than about 75° C., or less than about50° C. Such a mean operating temperature generally should be determinedafter an apparatus 300, 700 has been on and warmed up, such as providedits maximum light output for at least about 10 minutes, for example andwithout limitation, and may be measured in increments (andarithmetically averaged) using a commercially available infraredthermometer, under typical ambient conditions, such as an ambienttemperature of about 20-30° C., at the outermost surface of theapparatus 300, 700.

The exemplary base 305, 305A as illustrated in the various Figures havea form factor which is substantially flat in an overall sense, such ascomprising a sheet of a selected material (e.g., paper or plastic) whichmay be fed through a printing press, for example and without limitation,and which may have a topology on a first surface (or side) whichincludes surface roughness, cavities, channels or grooves or having afirst surface which is substantially smooth within a predeterminedtolerance (and does not include cavities, channels or grooves). Thosehaving skill in the art will recognize that innumerable, additionalshapes and surface topologies are available, are considered equivalentand within the scope of the disclosure.

For an apparatus 300, 720, 730 embodiment, one or more first conductors310 are then applied or deposited (on a first side or surface of thebase 305), or are applied over the diodes 100L for an apparatus 700,740, 750 embodiment, such as through a printing process, to a thicknessdepending upon the type of conductive ink or polymer, such as to about0.1 to 15 microns (e.g., about 10-12 microns wet film thickness for atypical silver or nanoparticle silver ink, with a dried or cured filmthickness of about 0.2 or 0.3 to 1.0 microns). In other exemplaryembodiments, depending upon the applied thickness, the first conductors310 also may be sanded to smooth the surface and also may becalendarized to compress the conductive particles, such as silver. In anexemplary method of manufacturing the exemplary apparatus 300, 700, 720,730, 740, 750, 760, 770, a conductive ink, polymer, or other conductiveliquid or gel (such as a silver (Ag) ink or polymer, a nanoparticle ornanofiber silver ink composition, a carbon nanotube ink or polymer, orsilver/carbon mixture such as amorphous nanocarbon (having particlesizes between about 75-100 nm) dispersed in a silver ink) is depositedon a base 305 or over the diodes 100L, such as through a printing orother deposition process, and may be subsequently cured or partiallycured (such as through an ultraviolet (uv) curing process), to form theone or more first conductors 310. In another exemplary embodiment, theone or more first conductors 310 may be formed by sputtering, spincasting (or spin coating), vapor deposition, or electroplating of aconductive compound or element, such as a metal (e.g., aluminum, copper,silver, gold, nickel). Combinations of different types of conductorsand/or conductive compounds or materials (e.g., ink, polymer, elementalmetal, etc.) may also be utilized to generate one or more compositefirst conductors 310. Multiple layers and/or types of metal or otherconductive materials may be combined to form the one or more firstconductors 310, such as first conductors 310 comprising gold plate overnickel, for example and without limitation. For example, vapor-depositedaluminum or silver, or mixed carbon-silver inks, may be utilized. Invarious exemplary embodiments, a plurality of first conductors 310 aredeposited, and in other embodiments, a first conductor 310 may bedeposited as a single conductive sheet or otherwise attached (e.g., asheet of aluminum coupled to a base 305) (not separately illustrated).Also in various embodiments, conductive inks or polymers which may beutilized to form the one or more first conductors 310 may not be curedor may be only partially cured prior to deposition of a plurality ofdiodes 100-100K, and then fully cured while in contact with theplurality of diodes 100-100K, such as for creation of ohmic contactswith the plurality of diodes 100-100K. In an exemplary embodiment, theone or more first conductors 310 are fully cured prior to deposition ofthe plurality of diodes 100-100K, with other compounds of the diode inkproviding some dissolving of the one or more first conductors 310 whichsubsequently re-cures in contact with the plurality of diodes 100-100K,and for an apparatus 700 embodiment, the one or more first conductors310 are fully cured following deposition. Also for an apparatus 700embodiment, a conductive ink having a lower concentration of conductiveparticles may also be utilized to form the one or more first conductors310, to facilitate dewetting from the first terminal 125. Depending uponthe selected embodiment, an optically transmissive conductive materialmay also be utilized to form the one or more first conductors 310.

Other conductive inks or materials may also be utilized to form the oneor more first conductors 310, second conductor(s) 320, third conductors(not separately illustrated), and any other conductors discussed below,such as copper, tin, aluminum, gold, noble metals, carbon, carbon black,carbon nanotube (“CNT”), single or double or multi-walled CNTs,graphene, graphene platelets, nanographene platelets, nanocarbon andnanocarbon and silver compositions, nano particle and nano fiber silvercompositions with good or acceptable optical transmission, or otherorganic or inorganic conductive polymers, inks, gels or other liquid orsemi-solid materials. In an exemplary embodiment, carbon black (having aparticle diameter of about 100 nm) is added to a silver ink to have aresulting carbon concentration in the range of about 0.025% to 0.5%, toenhance the ohmic contact and adhesion between the diodes 100-100L andthe first conductors 310. In addition, any other printable or coatableconductive substances may be utilized equivalently to form the firstconductor(s) 310, second conductor(s) 320 and/or third conductors, andexemplary conductive compounds include: (1) from Conductive Compounds(Londonberry, N.H., USA), AG-500, AG-800 and AG-510 Silver conductiveinks, which may also include an additional coating UV-1006S ultravioletcurable dielectric (such as part of a first dielectric layer 125); (2)from DuPont, 7102 Carbon Conductor (if overprinting 5000 Ag), 7105Carbon Conductor, 5000 Silver Conductor, 7144 Carbon Conductor (with UVEncapsulants), 7152 Carbon Conductor (with 7165 Encapsulant), and 9145Silver Conductor; (3) from SunPoly, Inc., 128A Silver conductive ink,129A Silver and Carbon Conductive Ink, 140A Conductive Ink, and 150ASilver Conductive Ink; (4) from Dow Corning, Inc., PI-2000 Series HighlyConductive Silver Ink; (5) from Henkel/Emerson & Cumings, Electrodag725A; (6) Monarch M120 available from Cabot Corporation of Boston,Mass., USA, for use as a carbon black additive, such as to a silver inkto form a mixture of carbon and silver ink; (7) Acheson 725A conductivesilver ink (available from Henkel), alone or in combination withadditional silver nanofibers; and (8) Inktek PA-010 or PA-030nanoparticle or nanofiber silver screen printable conductive ink,available from Inktec. of Gyeonggi-do, Korea. As discussed below, thesecompounds may also be utilized to form other conductors, including thesecond conductor(s) 320 and any other conductive traces or connections.In addition, conductive inks and compounds may be available from a widevariety of other sources.

Conductive polymers which are substantially optically transmissive mayalso be utilized to form the one or more first conductors 310, and alsothe second conductor(s) 320 and/or third conductors. For example,polyethylene-dioxithiophene may be utilized, such as thepolyethylene-dioxithiophene commercially available under the trade name“Orgacon” from AGFA Corp. of Ridgefield Park, N.J., USA, in addition toany of the other transmissive conductors discussed below and theirequivalents. Other conductive polymers, without limitation, which may beutilized equivalently include polyaniline and polypyrrole polymers, forexample. In another exemplary embodiment, carbon nanotubes which havebeen suspended or dispersed in a polymerizable ionic liquid or otherfluids are utilized to form various conductors which are substantiallyoptically transmissive or transparent, such as one or more secondconductors 320. It should be noted that for an apparatus 300 embodiment,the one or more second conductors 320 are generally substantiallyoptically transmissive to provide greater light emission or absorptionon the first side of the apparatus and, for an apparatus 700 embodiment,the one or more second conductors 320 are generally not appreciablyoptically transmissive, to provide a comparatively lower electricalimpedance, unless light output is also desired on the first side. Insome exemplary apparatus 700 embodiments, the one or more secondconductors 320 are highly opaque and reflective to act as a mirror andincrease light output from the second side of the apparatus 700.

An optically transmissive conductive ink which has been utilized to formone or more second conductors 320 includes a transparent conductive inkcommercially available from NthDegree Technologies Worldwide, Inc. ofTempe, Ariz., USA and has been described in Mark D. Lowenthal et al.,U.S. Provisional Patent Application Ser. No. 61/447,160, filed Feb. 28,2011 and entitled “Metallic Nanofiber Ink Substantially TransparentConductor, and Fabrication Method”, the entire contents of which areincorporated herein by reference with the same full force and effect asif set forth in their entirety herein. Another transparent conductorincludes silver nanofibers (about 3% to 50% by weight, or moreparticularly about 4% to 40% by weight, or more particularly about 5% to30% by weight, or more particularly about 6% to 20% by weight, or moreparticularly about 5% to 15% by weight, or more particularly about 7% to13% by weight, or more particularly about 9% to 11% by weight, or moreparticularly about 10% by weight), in a mixture of solvents, such as1-butanol, cyclohexanol, glacial acetic acid (about 1% by weight), andpolyvinyl pyrrolidone (about a 1 million MW) (about 2% to 4% by weight,or more particularly about 3% by weight). Another conductive ink mayalso comprise a nanoparticle or nanofiber silver ink (such as InktekPA-010 or PA-030 nanoparticle or nanofiber silver screen printableconductive ink), about 30% to 50% by weight, mixed with a plurality ofother solvents, such as with about 50% to 65% by weight of propyleneglycol, and about 1% to 10% by weight of n-propanol or1-methoxy-2-propanol. Another conductive ink may also comprise ananoparticle or nanofiber silver ink (such as Inktek PA-010 or PA-030nanoparticle or nanofiber silver screen printable conductive ink), witha silver concentration of about 0.30% to 3.0% by weight, mixed with aplurality of other solvents, as mentioned above.

Organic semiconductors, variously called π-conjugated polymers,conducting polymers, or synthetic metals, are inherently semiconductivedue to π-conjugation between carbon atoms along the polymer backbone.Their structure contains a one-dimensional organic backbone whichenables electrical conduction following n− or p+ type doping.Well-studied classes of organic conductive polymers includepoly(acetylene)s, poly(pyrrole)s, poly(thiophene)s, polyanilines,polythiophenes, poly(p-phenylene sulfide), poly(para-phenylenevinylene)s (PPV) and PPV derivatives, poly(3-alkylthiophenes),polyindole, polypyrene, polycarbazole, polyazulene, polyazepine,poly(fluorene)s, and polynaphthalene. Other examples includepolyaniline, polyaniline derivatives, polythiophene, polythiophenederivatives, polypyrrole, polypyrrole derivatives, polythianaphthene,polythianaphthane derivatives, polyparaphenylene, polyparaphenylenederivatives, polyacetylene, polyacetylene derivatives, polydiacethylene,polydiacetylene derivatives, polyparaphenylenevinylene,polyparaphenylenevinylene derivatives, polynaphthalene, andpolynaphthalene derivatives, polyisothianaphthene (PITN),polyheteroarylenvinylene (ParV), in which the heteroarylene group canbe, e.g., thiophene, furan or pyrrol, polyphenylene-sulphide (PPS),polyperinaphthalene (PPN), polyphthalocyanine (PPhc) etc., and theirderivatives, copolymers thereof and mixtures thereof. As used herein,the term derivatives means the polymer is made from monomers substitutedwith side chains or groups.

The method for polymerizing the conductive polymers is not particularlylimited, and the usable methods include uv or other electromagneticpolymerization, heat polymerization, electrolytic oxidationpolymerization, chemical oxidation polymerization, and catalyticpolymerization, for example and without limitation. The polymer obtainedby the polymerizing method is often neutral and not conductive untildoped. Therefore, the polymer is subjected to p-doping or n-doping to betransformed into a conductive polymer. The semiconductor polymer may bedoped chemically, or electrochemically. The substance used for thedoping is not particularly limited; generally, a substance capable ofaccepting an electron pair, such as a Lewis acid, is used. Examplesinclude hydrochloric acid, sulfuric acid, organic sulfonic acidderivatives such as parasulfonic acid, polystyrenesulfonic acid,alkylbenzenesulfonic acid, camphorsulfonic acid, alkylsulfonic acid,sulfosalycilic acid, etc., ferric chloride, copper chloride, and ironsulfate.

It should be noted that for a “reverse” build of the apparatus 300, thebase 305 and the one or more first conductors 310 are selected to beoptically transmissive, for light to enter and/or exit through thesecond side of the base 305. In addition, when the second conductor(s)320 are also transparent, light may be emitted or absorbed from or inboth sides of the apparatus 300.

Various textures may be provided for the one or more first conductors310, such as having a comparatively smooth surface, or conversely, arough or spiky surface, or an engineered micro-embossed structure (e.g.,available from Sappi, Ltd.) to potentially improve the adhesion of otherlayers (such as the dielectric layer 315 and/or to facilitate subsequentforming of ohmic contacts with diodes 100-100L. One or more firstconductors 310 may also be given a corona treatment prior to depositionof the diodes 100-100L, which may tend to remove any oxides which mayhave formed, and also facilitate subsequent forming of ohmic contactswith the plurality of diodes 100-100L. Those having skill in theelectronic or printing arts will recognize innumerable variations in theways in which the one or more first conductors 310 may be formed, withall such variations considered equivalent and within the scope of thedisclosure. For example, the one or more first conductors 310 may alsobe deposited through sputtering or vapor deposition, without limitation.In addition, for other various embodiments, the one or more firstconductors 310 may be deposited as a single or continuous layer, such asthrough coating, printing, sputtering, or vapor deposition.

As a consequence, as used herein, “deposition” includes any and allprinting, coating, rolling, spraying, layering, sputtering, plating,spin casting (or spin coating), vapor deposition, lamination, affixingand/or other deposition processes, whether impact or non-impact, knownin the art. “Printing” includes any and all printing, coating, rolling,spraying, layering, spin coating, lamination and/or affixing processes,whether impact or non-impact, known in the art, and specificallyincludes, for example and without limitation, screen printing, inkjetprinting, electro-optical printing, electroink printing, photoresist andother resist printing, thermal printing, laser jet printing, magneticprinting, pad printing, flexographic printing, hybrid offsetlithography, Gravure and other intaglio printing, for example. All suchprocesses are considered deposition processes herein and may beutilized. The exemplary deposition or printing processes do not requiresignificant manufacturing controls or restrictions. No specifictemperatures or pressures are required. Some clean room or filtered airmay be useful, but potentially at a level consistent with the standardsof known printing or other deposition processes. For consistency,however, such as for proper alignment (registration) of the varioussuccessively deposited layers forming the various embodiments,relatively constant temperature (with a possible exception, discussedbelow) and humidity may be desirable. In addition, the various compoundsutilized may be contained within various polymers, binders or otherdispersion agents which may be heat-cured or dried, air dried underambient conditions, or IR or uv cured.

It should also be noted, generally for any of the applications ofvarious compounds herein, such as through printing or other deposition,the surface properties or surface energies may also be controlled, suchas through the use of resist coatings or by otherwise modifying the“wetability” of such a surface, for example, by modifying thehydrophilic, hydrophobic, or electrical (positive or negative charge)characteristics, for example, of surfaces such as the surface of thebase 305, the surfaces of the various first or second conductors (310,320, respectively), and/or the surfaces of the diodes 100-100L. Inconjunction with the characteristics of the compound, suspension,polymer or ink being deposited, such as the surface tension, thedeposited compounds may be made to adhere to desired or selectedlocations, and effectively repelled from other areas or regions.

For example and without limitation, the plurality of diodes 100-100L aresuspended in a liquid, semi-liquid or gel carrier using any evaporativeor volatile organic or inorganic compound, such as water, an alcohol, anether, etc., which may also include an adhesive component, such as aresin, and/or a surfactant or other flow aid. In an exemplaryembodiment, for example and without limitation, the plurality of diodes100-100L are suspended as described above in the Examples. A surfactantor flow aid may also be utilized, such as octanol, methanol,isopropanol, or deionized water, and may also use a binder such as ananisotropic conductive binder containing substantially or comparativelysmall nickel beads (e.g., 1 micron) (which provides conduction aftercompression and curing and may serve to improve or enhance creation ofohmic contacts, for example), or any other uv, heat or air curablebinder or polymer, including those discussed in greater detail below(and which also may be utilized with dielectric compounds, lenses, andso on).

In addition, the various diodes 100-100L may be configured, for example,as light emitting diodes having any of various colors, such as red,green, blue, yellow, amber, etc. Light emitting diodes 100-100L havingdifferent colors may then be mixed within an exemplary diode ink, suchthat when energized in an apparatus 300, 300A, a selected colortemperature is generated.

Dried or Cured Diode Ink Example 1

-   -   A composition comprising:    -   a plurality of diodes 100-100L; and    -   a cured or polymerized resin or polymer.

Dried or Cured Diode Ink Example 2

-   -   A composition comprising:    -   a plurality of diodes 100-100L; and    -   a cured or polymerized resin or polymer forming a film at least        partially surrounding each diode and having a thickness between        about 10 nm and 300 nm.

Dried or Cured Diode Ink Example 3

-   -   A composition comprising:    -   a plurality of diodes 100-100L; and    -   at least trace amounts of a cured or polymerized resin or        polymer.

Dried or Cured Diode Ink Example 4

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a cured or polymerized resin or polymer; and    -   at least trace amounts of a solvent.

Dried or Cured Diode Ink Example 5

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   at least trace amounts of a cured or polymerized resin or        polymer; and    -   at least trace amounts of a solvent.

Dried or Cured Diode Ink Example 6

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   a cured or polymerized resin or polymer;    -   at least trace amounts of a solvent; and    -   at least trace amounts of a surfactant.

Dried or Cured Diode Ink Example 7

-   -   A composition comprising:    -   a plurality of diodes 100-100L;    -   at least trace amounts of a cured or polymerized resin or        polymer;    -   at least trace amounts of a solvent; and    -   at least trace amounts of a surfactant.

The diode ink (suspended diodes 100-100L and optional inert particles)is then deposited over the base 305A for an apparatus 700 embodiment, orover the one or more first conductors 310 for an apparatus 300embodiment, such as by printing using a 280 mesh polyester orPTFE-coated screen, and the volatile or evaporative components aredissipated, such as through a heating, uv cure or any drying process,for example, to leave the diodes 100-100L substantially or at leastpartially in contact with and adhering to the base 305A or the one ormore first conductors 310. In an exemplary embodiment, the depositeddiode ink is cured at about 110° C., typically for 5 minutes or less.The remaining dried or cured diode ink, as in Dried or Cured Diode InkExamples 1 and 2, generally comprises a plurality of diodes 100-100L anda cured or polymerized resin or polymer (at least in trace amounts)(which, as mentioned above, may general secure or hold the diodes100-100L in place) and form a film 295, as previously discussed. Whilethe volatile or evaporative components (such as first and/or secondsolvents and/or surfactants) are substantially dissipated, trace or moreamounts may remain, as illustrated in Dried or Cured Diode Ink Examples3-6. As used herein, a “trace amount” of an ingredient should beunderstood to be an amount greater than zero and less than or equal to5% of the amount of the ingredient originally present in the diode inkwhen initially deposited over the first conductors 310 and/or base 305,305A.

The resulting density or concentration of diodes 100-100L, as the numberof diodes 100-100L per square centimeter, for example, in the completedapparatus (300, 300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740,750, 760, 770), will vary depending upon the concentration of diodes100-100L in the diode ink. When the diodes 100-100L are in the range of20-30 microns in size, very high densities are available which stillcover only a small percentage of the surface area (one of the advantagesallowing greater heat dissipation without a separate need for heatsinks). For example, when the diodes 100-100L are in the range of 20-30microns in size are utilized, 10,000 diodes in a square inch covers onlyabout 1% of the surface area. Also for example, in an exemplaryembodiment, a wide variety of diode densities are available and withinthe scope of the disclosure for use in an apparatus 300, 300A, 300B,300C, 300D, 700, 700A, 700B, 720, 730, 740, 750, 760, 770, includingwithout limitation: 2 to 10,000 diodes 100-100L per square centimeter;or more specifically, 5 to 10,000 diodes 100-100L per square centimeter;or more specifically, 5 to 1,000 diodes 100-100L per square centimeter;or more specifically, 5 to 100 diodes 100-100L; or more specifically, 5to 50 diodes 100-100L per square centimeter; or more specifically, 5 to25 diodes 100-100L per square centimeter; or more specifically, 10 to8,000 diodes 100-100L per square centimeter; or more specifically, 15 to5,000 diodes 100-100L per square centimeter; or more specifically, 20 to1,000 diodes 100-100L per square centimeter; or more specifically, 25 to100 diodes 100-100L per square centimeter; or more specifically, 25 to50 diodes 100-100L per square centimeter.

Additional steps or several step processes may also be utilized fordeposition of the diodes 100-100L over the one or more first conductors310. Also for example and without limitation, a binder such as amethoxylated glycol ether acrylate monomer (which may also include awater soluble photoinitiator such TPO (triphosphene oxides)) or ananisotropic conductive binder may be deposited first, followed bydeposition of the diodes 100-100L which have been suspended in a liquidor gel as discussed above.

In an exemplary embodiment, for an apparatus 300, 720, 730, 760embodiment, the suspending medium for the diodes 100-100K may alsocomprise a dissolving solvent or other reactive agent, such as the oneor more dibasic esters, which initially dissolves or re-wets some of theone or more first conductors 310. When the suspension of the pluralityof diodes 100-100K is deposited and the surfaces of the one or morefirst conductors 310 then become partially dissolved or uncured, theplurality of diodes 100-100K may become slightly or partially embeddedwithin the one or more first conductors 310, also helping to form ohmiccontacts, and creating an adhesive bonding or adhesive coupling betweenthe plurality of diodes 100-100K and the one or more first conductors310. As the dissolving or reactive agent dissipates, such as throughevaporation, the one or more first conductors 310 re-hardens (orre-cures) in substantial contact with the plurality of diodes 100-100K.In addition to the dibasic esters discussed above, exemplary dissolving,wetting or solvating agents, for example and without limitation, also asmentioned above, include propylene glycol monomethyl ether acetate(C₆H₁₂O₃) (sold by Eastman under the name “PM Acetate”), used in anapproximately 1:8 molar ratio (or 22:78 by weight) with 1-propanol (orisopropanol) to form the suspending medium, and a variety of dibasicesters, and mixtures thereof, such as dimethyl succinate, dimethyladipate and dimethyl glutarate (which are available in varying mixturesfrom Invista under the product names DBE, DBE-2, DBE-3, DBE-4, DBE-5,DBE-6, DBE-9 and DBE-IB). In an exemplary embodiment, DBE-9 has beenutilized. The molar ratios of solvents will vary based upon the selectedsolvents, with 1:8 and 1:12 being typical ratios. Various compounds orother agents may also be utilized to control this reaction: for example,the combination or mixture of 1-propanol and water may apparentlysuppress the dissolving or re-wetting of the one or more firstconductors 310 by DBE-9 until comparatively later in the curing processwhen various compounds of the diode ink have evaporated or otherwisedissipated and the thickness of the diode ink is less than the height ofthe diodes 100-100K, so that any dissolved material (such as silver inkresin and silver ink particles) of the first conductors 310 are notdeposited on the upper surface of the diodes 100-100K (which are thencapable of forming electrical contacts with the second conductor(s)320).

Dielectric Ink Example 1

-   -   A composition comprising:    -   a dielectric resin comprising about 0.5% to about 30%        methylcellulose resin;    -   a first solvent comprising an alcohol; and    -   a surfactant.

Dielectric Ink Example 2

-   -   A composition comprising:    -   a dielectric resin comprising about 4% to about 6%        methylcellulose resin;    -   a first solvent comprising about 0.5% to about 1.5% octanol;    -   a second solvent comprising about 3% to about 5% IPA; and    -   a surfactant.

Dielectric Ink Example 3

-   -   A composition comprising:    -   about 10% to about 30% dielectric resin;    -   a first solvent comprising a glycol ether acetate;    -   a second solvent comprising a glycol ether; and    -   a third solvent.

Dielectric Ink Example 4

-   -   A composition comprising:    -   about 10% to about 30% dielectric resin;    -   a first solvent comprising about 35% to 50% ethylene glycol        monobutyl ether acetate;    -   a second solvent comprising about 20% to 35% dipropylene glycol        monomethyl ether; and    -   a third solvent comprising about 0.01% to 0.5% toluene.

Dielectric Ink Example 5

-   -   A composition comprising:    -   about 15% to about 20% dielectric resin;    -   a first solvent comprising about 35% to 50% ethylene glycol        monobutyl ether acetate;    -   a second solvent comprising about 20% to 35% dipropylene glycol        monomethyl ether; and    -   a third solvent comprising about 0.01% to 0.5% toluene.

Dielectric Ink Example 6

-   -   A composition comprising:    -   about 10% to about 30% dielectric resin;    -   a first solvent comprising about 50% to 85% dipropylene glycol        monomethyl ether; and    -   a second solvent comprising about 0.01% to 0.5% toluene.

Dielectric Ink Example 7

-   -   A composition comprising:    -   about 15% to about 20% dielectric resin;    -   a first solvent comprising about 50% to 90% ethylene glycol        monobutyl ether acetate; and    -   a second solvent comprising about 0.01% to 0.5% toluene.

Dielectric Ink Example 8

-   -   A composition comprising:    -   about 15% to about 20% dielectric resin;    -   a first solvent comprising about 50% to 85% dipropylene glycol        monomethyl ether; and    -   the balance comprising a second solvent comprising about 0.01%        to 8.0% propylene glycol or deionized water.

An insulating material (referred to as a dielectric ink, such as thosedescribed as Dielectric Ink Examples 1-8) is then deposited over thediodes 100-100L or the peripheral or lateral portions of the diodes100-100L to form an insulating or dielectric layer 315, such as througha printing or coating process, prior to deposition of secondconductor(s) 320. The dielectric layer 315 has a wet film thickness onthe order of about 30 to 40 microns and a dried or cured film thicknesson the order of about 5 to 7 microns. The insulating or dielectric layer315 may be comprised of any of the insulating or dielectric compoundssuspended in any of various media, as discussed above and below. In anexemplary embodiment, insulating or dielectric layer 315 comprises amethylcellulose resin, in an amount ranging from about 0.5% to 15%, ormore specifically about 1.0% to about 8.0%, or more specifically about3.0% to about 6.0%, or more specifically about 4.5% to about 5.5%, suchas E-3 “methocel” available from Dow Chemical; with a surfactant in anamount ranging from about 0.1% to 1.5%, or more specifically about 0.2%to about 1.0%, or more specifically about 0.4% to about 0.6%, such as0.5% BYK 381 from BYK Chemie GmbH; in a suspension with a first solventin an amount ranging from about 0.01% to 0.5%, or more specificallyabout 0.05% to about 0.25%, or more specifically about 0.08% to about0.12%, such as about 0.1% octanol; and a second solvent in an amountranging from about 0.0% to 8%, or more specifically about 1.0% to about7.0%, or more specifically about 2.0% to about 6.0%, or morespecifically about 3.0% to about 5.0%, such as about 4% IPA, with thebalance being a third solvent such as deionized water. With the E-3formulation, four to five coatings are deposited, to create aninsulating or dielectric layer 315 having a total thickness on the orderof 6-10 microns, with each coating cured at about 110° C. for about fiveminutes. In other exemplary embodiments, the dielectric layer 315 may beIR (infrared) cured, uv cured, or both. Also in other exemplaryembodiments, different dielectric formulations may be applied asdifferent layers to form the insulating or dielectric layer 315; forexample and without limitation, a first layer of a solvent-based cleardielectric available from Henkel Corporation of Dusseldorf, Germany isapplied, such as Henkel BIK-20181-40A, Henkel BIK-20181-40B, and/orHenkel BIK-20181-24B followed by the water-based E-3 formulationdescribed above, to form the dielectric layer 315. In other exemplaryembodiments, other dielectric compounds are commercially available fromHenkel and may be utilized equivalently, such as in Dielectric InkExample 8. The dielectric layer 315 may be transparent but also mayinclude a comparatively low concentration of light diffusing, scatteringor reflective particles, as well as heat conductive particles such asaluminum oxide, for example and without limitation. In various exemplaryembodiments, the dielectric ink will also de-wet from the upper surfaceof the diodes 100-100L, leaving at least some of the first terminal 125or the second, back side of the diodes 100-100K (depending on theorientation) exposed for subsequent contact with the second conductor(s)320.

Exemplary one or more solvents may be used in the exemplary dielectricinks, for example and without limitation: water; alcohols such asmethanol, ethanol, N-propanol (including 1-propanol, 2-propanol(isopropanol), 1-methoxy-2-propanol), isobutanol, N-butanol (including1-butanol, 2-butanol), N-pentanol (including 1-pentanol, 2-pentanol,3-pentanol), N-octanol (including 1-octanol, 2-octanol, 3-octanol);ethers such as methyl ethyl ether, diethyl ether, ethyl propyl ether,and polyethers; esters such ethyl acetate, dimethyl adipate, propyleneglycol monomethyl ether acetate, dimethyl glutarate, dimethyl succinate,glycerin acetate, dibasic esters (e.g., Invista DBE-9); esters suchethyl acetate; glycols such as ethylene glycols, diethylene glycol,polyethylene glycols, propylene glycols, dipropylene glycols, glycolethers, glycol ether acetates, PM acetate (propylene glycol monomethylether acetate), dipropylene glycol monomethyl ether, ethylene glycolmonobutyl ether acetate; carbonates such as propylene carbonate;glycerols such as glycerin; acetonitrile, tetrahydrofuran (THF),dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide(DMSO); and mixtures thereof. In addition to water-soluble resins, othersolvent-based resins may also be utilized. One or more thickeners may beused, for example clays such as hectorite clays, garamite clays,organo-modified clays; saccharides and polysaccharides such as guar gum,xanthan gum; celluloses and modified celluloses such as hydroxymethylcellulose, methylcellulose, ethyl cellulose, propylmethylcellulose, methoxy cellulose, methoxy methylcellulose, methoxypropyl methylcellulose, hydroxy propyl methylcellulose, carboxymethylcellulose, hydroxy ethylcellulose, ethyl hydroxylethylcellulose,cellulose ether, cellulose ethyl ether, chitosan; polymers such asacrylate and (meth)acrylate polymers and copolymers, polyvinylpyrrolidone, polyethylene glycol, polyvinyl acetate (PVA), polyvinylalcohols, polyacrylic acids, polyethylene oxides, polyvinyl butyral(PVB); diethylene glycol, propylene glycol, 2-ethyl oxazoline, fumedsilica (such as Cabosil), silica powders and modified ureas such as BYK®420 (available from BYK Chemie). Other viscosity modifiers may be used,as well as particle addition to control viscosity, as described in Lewiset al., Patent Application Publication Pub. No. US 2003/0091647. Flowaids or surfactants may also be utilized, such as octanol and EmeraldPerformance Materials Foamblast 339, for example. In other exemplaryembodiments, one or more insulators 135 may polymeric, such ascomprising PVA or PVB in deionized water, typically less than 12percent.

Following deposition of insulating or dielectric layer 315, one or moresecond conductor(s) 320 are deposited (e.g., through printing aconductive ink, polymer, or other conductor such as metal), which may beany type of conductor, conductive ink or polymer discussed above, or maybe an optically transmissive (or transparent) conductor, to form anohmic contact with exposed or non-insulated portions of the diodes100-100L (generally, the first terminal 125 for diodes 100-100L in thefirst orientation). The one or more optically transmissive secondconductor(s) 320 have a wet film thickness on the order of about 6 to 18microns and a dried or cured film thickness on the order of about 0.1 to0.4 microns, and optically opaque one or more second conductor(s) 320(such as Acheson 725A conductive silver) generally have a wet filmthickness on the order of about 14 to 18 microns and a dried or curedfilm thickness on the order of about 5 to 8 microns. For example, anoptically transmissive second conductor may be deposited as a singlecontinuous layer (forming a single electrode), such as for lighting orphotovoltaic applications. For a reverse build mentioned above, and forthe apparatus 700 embodiments, the second conductor(s) 320 do not needto be, although they can be, optically transmissive, allowing light toenter or exit from both top and bottom sides of the apparatus 300, 300A,300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740, 750, 760, 770. Anoptically transmissive second conductor(s) 320 may be comprised of anycompound which: (1) has sufficient conductivity to energize or receiveenergy from the first or upper portions of the apparatus 300 (andgenerally with a sufficiently low resistance or impedance to reduce orminimize power losses and heat generation, as may be necessary ordesirable); and (2) has at least a predetermined or selected level oftransparency or transmissibility for the selected wavelength(s) ofelectromagnetic radiation, such as for portions of the visible spectrum.The choice of materials to form the optically transmissive ornon-transmissive second conductor(s) 320 may differ, depending on theselected application of the apparatus 300, 700 and depending upon theutilization of optional one or more third conductors. The one or moresecond conductor(s) 320 are deposited over exposed and/or non-insulatedportions of the diodes 100-100L, and/or also over any of the insulatingor dielectric layer 315, such as by using a printing or coating processas known or may become known in the printing or coating arts, withproper control provided for any selected alignment or registration, asmay be necessary or desirable.

For example, an exemplary transparent conductive ink utilized to formone or more second conductors 320 may comprise about 0.4-3.0% silvernanofibers (or more, in other embodiments), about 2-4% polyvinylpyrrolidone (1 million MW), 0.5-2% glacial acetic acid, with the balancebeing 1-butanol and/or cyclohexanol.

In an exemplary embodiment, in addition to the conductors describedabove, carbon nanotubes (CNTs), nanoparticle or nanofiber silvers,polyethylene-dioxithiophene (e.g., AGFA Orgacon), a combination ofpoly-3,4-ethylenedioxythiophene and polystyrenesulfonic acid (marketedas Baytron P and available from Bayer AG of Leverkusen, Germany), apolyaniline or polypyrrole polymer, indium tin oxide (ITO) and/orantimony tin oxide (ATO) (with the ITO or ATO typically suspended asparticles in any of the various binders, polymers or carriers previouslydiscussed) may be utilized to form optically transmissive secondconductor(s) 320. In an exemplary embodiment, carbon nanotubes aresuspended in a volatile liquid with a surfactant, such as carbonnanotube compositions available from SouthWest NanoTechnologies, Inc. ofNorman, Okla., USA. In addition, one or more third conductors (notseparately illustrated) having a comparatively lower impedance orresistance is or may be incorporated into corresponding transmissivesecond conductor(s) 320. For example, to form one or more thirdconductors, one or more fine wires may be formed using a conductive inkor polymer (e.g., a silver ink, CNT or a polyethylene-dioxithiophenepolymer) printed over corresponding sections or layers of thetransmissive second conductor(s) 320, or one or more fine wires (e.g.,having a grid or ladder pattern) may be formed using a conductive ink orpolymer printed over a larger, unitary transparent second conductor(s)320 in larger displays.

Other compounds which may be utilized equivalently to form substantiallyoptically transmissive second conductor(s) 320 include indium tin oxide(ITO) as mentioned above, and other transmissive conductors as arecurrently known or may become known in the art, including one or more ofthe conductive polymers discussed above, such aspolyethylene-dioxithiophene available under the trade name “Orgacon”,and various carbon and/or carbon nanotube-based transparent conductors.Representative transmissive conductive materials are available, forexample, from DuPont, such as 7162 and 7164 ATO translucent conductor.Transmissive second conductor(s) 320 may also be combined with variousbinders, polymers or carriers, including those previously discussed,such as binders which are curable under various conditions, such asexposure to ultraviolet radiation (uv curable).

An optional stabilization layer 335 may be deposited over the secondconductor(s) 320, as may be necessary or desirable, and is utilized toprotect the second conductor(s) 320, such as to prevent the luminescent(or emissive) layers 325 or any intervening conformal coatings fromdegrading the conductivity of the second conductor(s) 320. One or morecomparatively thin coatings of any of the inks, compounds or coatingsdiscussed below (with reference to protective coating 330) may beutilized, such as Nazdar 9727 clear base or DuPont 5018 or an infraredcurable resin such as about 7% polyvinylbutyral in cyclohexanol. Inaddition, heat dissipation and/or light scattering particles may also beoptionally included in the stabilization layer 335. An exemplarystabilization layer is typically about 10-40 microns, in dried or curedform.

As an option, carbon electrodes 322 (illustrated as 322A and 322B) maybe utilized to form contacts, external to the sealing or protectivelayer 330, to the one or more first conductors 310 and one or moresecond conductor(s) 320, as illustrated for various exemplaryembodiments, and helps to protect the one or more first conductors 310and one or more second conductor(s) 320 from corrosion and abrasion. Inan exemplary embodiment, a carbon ink is utilized, such as Acheson 440A,having a wet film thickness on the order of about 18 to 20 microns and adried or cured film thickness on the order of about 7 to 10 microns.

Also as an option illustrated in FIGS. 102 and 103, an optional thirdconductive layer 312 may be utilized, and may comprise any of theconductive materials described herein for one or more first conductors310 and/or one or more second conductor(s) 320.

One or more luminescent (or emissive) layers 325 (e.g., comprising oneor more phosphor layers or coatings) may be deposited over thestabilization layer 335 (or over the second conductor(s) 320 when nostabilization layer 335 is utilized), or directly on the second side ofthe base 305A for an apparatus 700 embodiment. Multiple luminescent (oremissive) layers 325 may also be utilized, as illustrated, such as oneon each side of an apparatus 300, 300A, 300C, 300D, 700, 700A, 720, 730,740, 750, 760, 770. In an exemplary embodiment, such as an LEDembodiment, one or more emissive layers 325 may be deposited, such asthrough printing or coating processes discussed above, over the entiresurface of the stabilization layer 335 (or over the second conductor(s)320 when no stabilization layer 335 is utilized), for an apparatus 300embodiment, or directly on the second side of the base 305A for anapparatus 700 embodiment, or both, for example and without limitation.The one or more emissive layers 325 may be formed of any substance orcompound capable of or adapted to emit light in the visible spectrum orto shift (e.g., stokes shift) the frequency of the emitted light (orother electromagnetic radiation at any selected frequency) in responseto light (or other electromagnetic radiation) emitted from diodes100-100L. For example, a yellow phosphor-based emissive layer 325 may beutilized with a blue light emitting diode 100-100L to produce asubstantially white light. Such luminescent compounds include variousphosphors, which may be provided in any of various forms and with any ofvarious dopants. The luminescent compounds or particles forming the oneor more emissive layers 325 may be utilized in or suspended in a polymerform having various binders, and also may be separately combined withvarious binders (such as phosphor binders available from DuPont orConductive Compounds), both to aid the printing or other depositionprocess, and to provide adhesion of the phosphor to the underlying andsubsequent overlying layers. The one or more emissive layers 325 mayalso be provided in either uv-curable or heat-curable forms.

A wide variety of equivalent luminescent or otherwise light emissivecompounds are available and are within the scope of the disclosure,including without limitation: (1) G1758, G2060, G2262, G3161, EG2762, EG3261, EG3560, EG3759, Y3957, EY4156, EY4254, EY4453, EY4651, EY4750,O5446, O5544, O5742, O6040, R630, R650, R6733, R660, R670, NYAG-1,NYAG-4, NYAG-2, NYAG-5, NYAG-3, NYAG-6, TAG-1, TAG-2, SY450-A, SY450-B,SY460-A, SY460-B, OG450-75, OG450-27, OG460-75, OG460-27, RG450-75,RG450-65, RG450-55, RG450-50, RG450-45, RG450-40, RG450-35, RG450-30,RG450-27, RG460-75, RG460-65, RG460-55, RG460-50, RG460-45, RG460-40,RG460-35, RG460-30, and RG460-27, available from Internatix of Fremont,Calif. USA; (2) 13C1380, 13D1380, 14C1220, and GG-84 available fromGlobal Tungsten & Powders Corp. of Towanda, Pa., USA; (3) FL63/S-D1,HPL63/F-F1, HL63/S-D1, QMK58/F-U1, QUMK58/F-D1, KEMK63/F-P1, CPK63/N-U1,ZMK58/N-D1, and UKL63/F-U1 available from Phosphor Technology Ltd. ofHerts, England; (4) BYW01A/PTCW01AN, BYW01B/PTCW01BN, BUVOR02, BUVG01,BUVR02, BUVY02, BUVG02, BUVR03/PTCR03, and BUVY03 available fromPhosphor Tech Corp. of Lithia Springs, Ga., USA; and (5) Hawaii655,Maui535, Bermuda465, and Bahama560 available from Lightscape Materials,Inc. of Princeton, N.J. USA. In addition, depending upon the selectedembodiment, colorants, dyes and/or dopants may be included within anysuch luminescent (or emissive) layer 325. In an exemplary embodiment, ayittrium aluminum garnet (“YAG”) phosphor is utilized, available fromPhosphor Technology Ltd. and from Global Tungsten & Powders Corp, suchas 40% YAG in a uv curable resin (with a wet and dry/cured filmthickness of about 40 to 100 microns), or 70% YAG in an infrared curableresin-solvent system, such as about 5% polyvinylbutyral in about 95%cyclohexanol (with a wet film thickness of about 15 to 17 microns anddry/cured film thickness of about 13 to 15 microns). In addition, thephosphors or other compounds utilized to form an emissive layer 325 mayinclude dopants which emit in a particular spectrum, such as green orblue. In those cases, the emissive layer may be printed to define pixelsfor any given or selected color, such as RGB or CMYK, to provide a colordisplay. Those having skill in the art will recognize that any of theapparatus 300 embodiments may also comprise such one or more emissivelayers 325 coupled to or deposited over the stabilization layer 335 orsecond conductor(s) 320.

Depending upon the solvents utilized in forming the one or more secondconductor(s) 320, an optional one or more barrier layers 318 may beutilized, as illustrated in FIG. 103, such as to prevent compounds ofthe one or more second conductor(s) 320 from penetrating through thedielectric layer 315 to the one or more first conductors 310. In anexemplary embodiment, a viscosity modifier is utilized, such as an E-10viscosity modifier or any of the other viscosity modifiers discussedabove, deposited to form a cured or dried film or membrane thickness ofabout 100 to 200 nm. Any of the materials utilized to form a protectiveor sealing coating 330 or stabilization layer 335 may also be utilizedto form the one or more barrier layers 318.

The apparatus 300 may also include an optional protective or sealingcoating 330 (which also may be combined with the optional stabilizationlayer 335), which may also include any type of lensing or lightdiffusion or dispersion structure or filter, such as a substantiallyclear plastic or other polymer, for protection from various elements,such as weather, airborn corrosive substances, etc., or such a sealingand/or protective function may be provided by the polymer (resin orother binder) utilized with the emissive layer 325. For ease ofillustration, FIGS. 76, 78-82, 87, 88, 91-98, 102 and 103 illustratesuch a polymer (resin or other binder) forming a protective or sealingcoating 330 using the dotted lines to indicate substantialtransparency.) In an exemplary embodiment, protective or sealing coating330 is deposited as one or more conformal coatings using aurethane-based material such as a proprietary resin available as NAZDAR9727 (www.nazdar.com) or a uv curable urethane acrylate PF 455 BCavailable from Henkel Corporation of Dusseldorf, Germany to a thicknessof between about 10-40 microns. In another exemplary embodiment,protective or sealing coating 330 is performed by laminating theapparatus 300. Not separately illustrated, but as discussed in relatedU.S. patent applications (U.S. patent application Ser. No. 12/560,334,U.S. patent application Ser. No. 12/560,340, U.S. patent applicationSer. No. 12/560,355, U.S. patent application Ser. No. 12/560,364, andU.S. patent application Ser. No. 12/560,371, incorporated in theirentireties herein by reference with the same full force and effect as ifset forth in their entireties herein), a plurality of lenses (suspendedin a polymer (resin or other binder)) also may be deposited directlyover the one or more emissive layers 325 and other features, to createany of the various light emitting apparatus 300 embodiments.

Those having skill in the art will recognize that any number of firstconductors 310, insulators 315, second conductors 320, etc., be utilizedwithin the scope of the claimed invention. In addition, there may be awide variety of orientations and configurations of the plurality offirst conductors 310, one or more of insulators (or dielectric layer)315, and a plurality of second conductor(s) 320 (with any incorporatedcorresponding and optional one or more third conductors) for any of theapparatuses 300, such as substantially parallel orientations, inaddition to the orientations illustrated. For example, a plurality offirst conductors 310 may be all substantially parallel to each other,and a plurality of second conductor(s) 320 also may be all substantiallyparallel to each other. In turn, the plurality of first conductors 310and plurality of second conductor(s) 320 may be perpendicular to eachother (defining rows and columns), such that their area of overlap maybe utilized to define a picture element (“pixel”) and may be separatelyand independently addressable. When either or both the plurality offirst conductors 310 and the plurality of second conductor(s) 320 may beimplemented as spaced-apart and substantially parallel lines having apredetermined width (both defining rows or both defining columns), theymay also be addressable by row and/or column, such as sequentialaddressing of one row after another, for example and without limitation.In addition, either or both the plurality of first conductors 310 andthe plurality of second conductor(s) 320 may be implemented as a layeror sheet as mentioned above.

As may be apparent from the disclosure, an exemplary apparatus 300,300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740, 750, 760, 770depending upon the choices of composite materials such as a base 305,may be designed and fabricated to be highly flexible and deformable,potentially even foldable, stretchable and potentially wearable, ratherthan rigid. For example, an exemplary apparatus 300, 300A, 300B, 300C,300D, 700, 700A, 700B, 720, 730, 740, 750, 760, 770, may compriseflexible, foldable, and wearable clothing, or a flexible lamp, or awallpaper lamp, without limitation. With such flexibility, an exemplaryapparatus 300, 300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730, 740,750, 760, 770, may be rolled, such as a poster, or folded like a pieceof paper, and fully functional when re-opened. Also for example, withsuch flexibility, an exemplary apparatus 300, 300A, 300B, 300C, 300D,700, 700A, 700B, 720, 730, 740, 750, 760, 770, may have many shapes andsizes, and be configured for any of a wide variety of styles and otheraesthetic goals. Such an exemplary apparatus 300, 300A, 300B, 300C,300D, 700, 700A, 700B, 720, 730, 740, 750, 760, 770, is alsoconsiderably more resilient than prior art devices, being much lessbreakable and fragile than, for example, a typical large screentelevision.

As indicated above, the plurality of diodes 100-100L may be configured(through material selection and corresponding doping) to be photovoltaic(PV) diodes or LEDs, as examples and without limitation. FIG. 84 is ablock diagram of a first exemplary system 350 embodiment, in which theplurality of diodes 100-100L are implemented as LEDs, of any type orcolor. The system 350 comprises a light emitting apparatus 300A, 300C,300D, 300C, 300D, 700A (and any of apparatuses 720, 730, 740, 750, 760,770 in which the diodes are LEDs), an interface circuit 355 couplable toa power source 340 (such as an AC line or a DC battery), and optionallya controller 345 (having control logic circuitry 360 and optionallymemory 365). (An apparatus 300A is otherwise generally the same as anapparatus 300 but have the plurality of diodes 100-100L implemented asLEDs, and double-sided, for apparatus 300C, 300D embodiments, andsimilarly, an apparatus 700A is otherwise generally the same as anapparatus 700 but has the plurality of diodes 100-100L implemented asLEDs.). When one or more first conductors 310 and one or more secondconductor(s) 320 (or third conductors 312) are energized, such asthrough the application of a corresponding voltage (e.g., from powersource 340), energy will be supplied to one or more of the plurality ofLEDs (diodes 100-100L), either entirely across the apparatus 300A, 300C,300D, 300C, 300D, 700A, 720, 730, 740, 750, 760, 770 when the conductorsand insulators are each implemented as single layers, or at thecorresponding intersections (overlapping areas) of the energized firstconductors 310 and second conductor(s) 320, which depending upon theirorientation and configuration, define a pixel, a sheet, or a row/column,for example. Accordingly, by selectively energizing the first conductors310 and second conductor(s) 320, the apparatus 300A (and/or system 350)provides a pixel-addressable, dynamic display, or a lighting device, orsignage, etc. For example, the plurality of first conductors 310 maycomprise a corresponding plurality of rows, with the plurality oftransmissive second conductor(s) 320 comprising a correspondingplurality of columns, with each pixel defined by the intersection oroverlapping of a corresponding row and corresponding column. When eitheror both the plurality of first conductors 310 and the plurality ofsecond conductor(s) 320 may be implemented as illustrated in FIGS.76-82, 87, 88, 91-98, 102, 103, also for example, energizing of theconductors 310, 320 will provide power to substantially all (or most) ofthe plurality of LEDs (diodes 100-100L), such as to provide lightemission for a lighting device or a static display, such as signage.Such a pixel count may be quite high, well above typical high definitionlevels.

Continuing to refer to FIG. 84, the apparatus 300A, 300C, 300D, 300C,300D, 700A, 720, 730, 740, 750, 760, 770 is coupled through an interfacecircuit 355 to a power source 340, which may be a DC power source (suchas a battery or a photovoltaic cell) or an AC power source (such ashousehold or building power), and also optionally to a controller 345.The interface circuit 355 may be embodied in a wide variety of ways,such as a full or half wave rectifier, impedance matching circuitry,capacitors to reduce DC ripple, a switching power supply for coupling toan AC line, etc., and may include a wide variety of components (notseparately illustrated) for controlling the energizing of the diodes100-100L, for example and without limitation. When the controller 345 isimplemented, such as for an addressable light emitting display system350 embodiment and/or a dynamic light emitting display system 350embodiment, the controller 345 may be utilized to control the energizingof the diodes 100-100L (via the various pluralities of first conductors310 and the plurality of transmissive second conductor(s) 320) as knownor becomes known in the electronic arts, and typically comprises controllogic circuitry 360 (which may be combinational logic circuitry, afinite state machine, a processor, etc.), and a memory 365. Otherinput/output (I/O) circuitry may also be utilized. When the controller345 is not implemented, such as for various lighting system 350embodiments (which are typically non-addressable and/or a non-dynamiclight emitting display system 350 embodiments), the system 350 istypically coupled to an electrical or electronic switch (not separatelyillustrated), which may comprise any suitable type of switchingarrangement, such as for turning on, off, and/or dimming a lightingsystem. The Control logic circuitry 360, memory 365 are discussed ingreater detail below, following the discussion of FIGS. 100-103, 85 and86.

The interface circuit 355 may be implemented as known or may becomeknown in the art, and may include impedance matching capability, voltagerectification circuitry, voltage translation for a low voltage processorto interface with a higher voltage control bus for example, variousswitching mechanisms (e.g., transistors) to turn various lines orconnectors on or off in response to signaling from the control logiccircuitry 360, and/or physical coupling mechanisms. In addition, theinterface circuit 355 may also be adapted to receive and/or transmitsignals externally to the system 350, such as through hard-wiring or RFsignaling, for example, to receive information in real-time to control adynamic display, for example, or to control brightness of light output(dimming), also for example. The interface circuit 355A also may bestand-alone device (e.g., modular) and re-usable, for example, with theapparatus 760, 770 configured to snap, screw, lock, or otherwise coupleto the interface circuit 355A, so that the interface circuit 355A may beused repeatedly over time with multiple replacement apparatuses 760,770.

For example, as illustrated in FIG. 100, an exemplary system embodiment800, 810 comprises an apparatus 760 (if implemented using diodes100-100K) or an apparatus 770 (if implemented using diodes 100L), inwhich the plurality of diodes 100-100L are light emitting diodes, and aninterface circuit 355 to fit any of the various standard Edison socketsfor light bulbs. Continuing with the example and without limitation, theinterface circuit 355 may be sized and shaped to conform to one or moreof the standardized screw configurations, such as the E12, E14, E26,and/or E27 screw base standards, such as a medium screw base (E26) or acandelabra screw base (E12), and/or the other various standardspromulgated by the American National Standards Institute (“ANSI”) and/orthe Illuminating Engineering Society, also for example. In otherexemplary embodiments, the interface circuit 355 may be sized and shapedto conform to a standard fluorescent bulb socket or a two plug base,such as a GU-10 base, also for example and without limitation. Such anexemplary system embodiment also may be viewed equivalently as anothertype of apparatus, particularly when having a form factor compatible forinsertion into an Edison or fluorescent socket, for example and withoutlimitation.

For example, an LED-based “light bulb” may be formed having a designwhich resembles a traditional incandescent light bulb, having ascrew-type connection as part of interface circuit 355, such as ES, E27,SES, or E14, which may be adapted to connect with any power socket type,e.g., L1, PL-2 pin, PL-4 pin, G9 halogen capsule, G4 halogen capsule,GU10, GU5.3, bayonet, small bayonet, or any other connection known inthe art, for example and without limitation.

The apparatus 300A, 300C, 300D, 700 and first system 350 may be used toform a wide variety of lighting devices or other illuminating products,for many purposes, as light bulbs and tubes, lamps, lighting fixtures,indoor and outdoor lighting, lamps configured to have a lamp shade formfactor, architectural lighting, work or task lighting, decorative ormood lighting, overhead lighting, safety lighting, dimmable lighting,colored lighting, theatrical and/or color-changeable lighting, displaylighting, and lighting having any of the various decorative or fancifulforms mentioned herein. Not separately illustrated, the first system 350will generally also include various mechanical structures to providesufficient physical support of the apparatus 300A, 300C, 300D, in anydesired shape or form within a system 350.

Referring to FIG. 100, the exemplary system 800 comprises an apparatus760 and an interface circuit 355A, and the exemplary system 810comprises an apparatus 770 and an interface circuit 355A. The interfacecircuit 355A has been configured to fit in a standard, Edison bulbscrew-type socket for coupling to a standard AC power source, such as anAC mains (not separately illustrated). Such an interface circuit 355Awill typically comprise rectification circuitry to convert an AC voltageto a DC voltage, and may also include impedance matching circuitry andvarious capacitors and/or resistors (and often switches implementedusing transistors) to reduce ripple of the DC voltage, as known in thefield of LED lighting and LED power supplies. As illustrated in FIGS.102 and 103, the apparatus 760 is comprised of a plurality of diodes100-100K, while the apparatus 770 is comprised of a plurality of diodes100L, with corresponding differences in apparatus structure andmaterials, as discussed above and as discussed in greater detail below.FIG. 100 also serves to illustrate the extremely thin and flexible formfactor of an exemplary apparatus (300, 300A, 300B, 300C, 300D, 300C,300D, 700, 700A, 700B, 720, 730, 740, 750, 760, 770), which has beentwisted and folded into a fanciful, decorative form.

FIG. 101 is a plan view illustrating the printed layout of an apparatus760, 770. As illustrated, the apparatus 760, 770 is printed as a flatsheet with a very thin form factor, and is then die cut in the regions716, forming comparatively narrow lamp strips 717 (coupled in series, asdescribed above). Electrodes (illustrated as carbon electrodes 322A,322B) are provided at each end. The apparatus 760, 770 is then curledand ends 718 of the lamp strips 717 are gathered together and overlappedwith each other in a circle, with access to the electrodes 322A and 322Bto provide power to the apparatus 760, 770 through the interface circuit355A, and with the lamp strips 717 having some separation from eachother, as illustrated in FIG. 100.

Referring to FIG. 102, an apparatus 760 is similar to the otherillustrated apparatuses, with the addition of two more layers, namely,one or more third conductors 312 (which also may be deposited as asingle layer using any of the transparent or nontransparent conductiveinks and compounds discussed herein), and an additional dielectric layer(illustrated as 315A, to distinguish it from the other dielectric layer,illustrated as 315B), between the one or more third conductors 312 andthe one or more first conductors 310. The one or more third conductors312 are utilized to provide power (e.g., a voltage level) along theedges of the lamp strips 717 and are coupled to the one or more secondconductors 320, which may be deposited as a layer of transparentconductive material as discussed above, and provides a method to reducethe overall impedance, current levels and power consumption of theapparatus 760, effectively functioning as parallel busbars along thelength of each lamp strip 717.

Referring to FIG. 103, an apparatus 770 is also similar to the otherillustrated apparatuses, with the addition of three more layers: (1) oneor more third conductors 312 (which also may be deposited as a singlelayer using any of the transparent or nontransparent conductive inks andcompounds discussed herein); (2) an additional dielectric layer(illustrated as 315A, to distinguish it from the other dielectric layer,illustrated as 315B), between the one or more third conductors 312 andthe one or more second conductors 320; and (3) one or more barrierlayers 318, as mentioned above, deposited between the dielectric layer315B and the one or more second conductors 320. The one or more thirdconductors 312 are utilized to provide power (e.g., a voltage level)along the edges of the lamp strips 717 and are coupled to the one ormore first conductors 310, and also provides a method to reduce theoverall impedance, current levels and power consumption of the apparatus770, also effectively functioning as parallel busbars along the lengthof each lamp strip 717.

Any of various levels of light output may be provided by an apparatus300A, 300C, 300D, 300C, 300D, 700A, 720, 730, 740, 750, 760, 770, andwill generally vary based on the concentration of diodes 100-100Lutilized, the number of apparatuses 300A, 300C, 300D, 300C, 300D, 700A,720, 730, 740, 750, 760, 770 utilized in a first system 350, selected orallowed power consumption, and the applied voltage and/or currentlevels. In an exemplary embodiment, an apparatus 300A, 300C, 300D, 300C,300D, 700A, 720, 730, 740, 750, 760, 770 may provide light output in therange of about 25 to 1300 lumens, for example and without limitation,depending upon the power consumption, the concentration or density ofthe diodes 100-100L, the current levels of the diodes 100-100L currentlevels (i.e., how hard the diodes 100-100L are driven), overallimpedance levels, etc.

As indicated above, the plurality of diodes 100-100L also may beconfigured (through material selection and corresponding doping) to bephotovoltaic (PV) diodes. FIG. 85 is a block diagram of a secondexemplary system 375 embodiment, in which the diodes 100-100L areimplemented as photovoltaic (PV) diodes. The system 375 comprises anapparatus 300B, 700B (which is otherwise generally the same as anapparatus 300, 700 (or any of the other illustrated apparatuses) buthaving the plurality of diodes 100-100L implemented as photovoltaic (PV)diodes), and either or both an energy storage device 380, such as abattery, or an interface circuit 385 to deliver power or energy toanother system (not separately illustrated), for example, such as amotorized device or an electric utility. (In other exemplary embodimentswhich do not comprise an interface circuit 385, other circuitconfigurations may be utilized to provide energy or power directly tosuch an energy using apparatus or system or energy distributingapparatus or system.) Within the system 375, the one or more firstconductors 310 (or electrodes 322A) of an apparatus 300B, 700B arecoupled to form a first terminal (such as a negative or positiveterminal), and the one or more second conductor(s) 320 (or electrodes322B) of the apparatus 300B, 700B are coupled to form a second terminal(such as a correspondingly positive or negative terminal), which arethen couplable for connection to either or both an energy storage device380 or an interface circuit 385. When light (such as sunlight) isincident upon the apparatus 300B, 700B, the light may be concentrated onone of more photovoltaic (PV) diodes 100-100L which, in turn, convertthe incident photons to electron-hole pairs, resulting in an outputvoltage generated across the first and second terminals, and output toeither or both an energy storage device 380 or an interface circuit 385.

It should be noted that when the first conductors 310 have theinterdigitated or comb structure illustrated in FIG. 77, the secondconductor 320 may be energized using first conductor 310B or, similarly,a generated voltage may be received across first conductors 310A and310B.

FIG. 86 is a flow diagram illustrating an exemplary method embodimentfor apparatus 300, 300A, 300B, 300C, 300D, 700, 700A, 700B, 720, 730,740, 750, 760, 770 fabrication, and provides a useful summary. Beginningwith start step 400, one or more first conductors (310) are depositedonto a base (305), such as by printing a conductive ink or polymer orvapor depositing, sputtering or coating the base (305) with one or moremetals, followed by curing or partially curing the conductive ink orpolymer, or potentially removing a deposited metal from unwantedlocations, depending upon the implementation, step 405. A plurality ofdiodes 100-100L, having typically been suspended in a liquid, gel orother compound or mixture (e.g., suspended in diode ink), which also mayinclude a plurality of inert particles 292, are then deposited over theone or more first conductors, step 410, also typically through printingor coating, to form an ohmic contact between the plurality of diodes100-100L and the one or more first conductors (which may also involvevarious chemical reactions, compression and/or heating, for example andwithout limitation). For an apparatus 700 embodiment, steps 405 and 410occur in the opposite order, as discussed above.

A dielectric or insulating material, such as a dielectric ink, is thendeposited on or about the plurality of diodes 100-100L, such as aboutthe periphery of the diodes 100-100L (and cured or heated), step 415, toform one or more insulators or dielectric layer 315. For an apparatus760 embodiment, not separately illustrated, one or more third conductors312 and a dielectric layer 315A may be deposited, as a step 405 and 415,then followed by another step 405 and a step 410. For an apparatus 770embodiment, a barrier layer 318 may also be deposited, also notseparately illustrated. Next, one or more second conductors 320 (whichmay or may not be optically transmissive) are then deposited over andform contacts with the plurality of diodes 100-100L, such as over thedielectric layer 315 and about the upper surface of the diodes 100-100Land cured (or heated), step 420, also to form ohmic contacts between theone or more second conductors (320) and the plurality of plurality ofdiodes 100-100L. In exemplary embodiments, such as for an addressabledisplay, a plurality of (transmissive) second conductors 320 areoriented substantially perpendicular to a plurality of first conductors310. For an apparatus 770 embodiment, not separately illustrated, adielectric layer 315A may be deposited, as a step 415, followed bydepositing one or more third conductors 312, as a step 405.

As another option, before or during step 420, testing may be performed,with non-functioning or otherwise defective diodes 100-100L removed ordisabled. For example, for PV diodes, the surface (first side) of thepartially completed apparatus may be scanned with a laser or other lightsource and, when a region (or individual diode 100-100L) does notprovide the expected electrical response, it may be removed using a highintensity laser or other removal technique. Also for example, for lightemitting diodes which have been powered on, the surface (first side) maybe scanned with a photosensor, and, when a region (or individual diode100-100L) does not provide the expected light output and/or drawsexcessive current (i.e., current in excess of a predetermined amount),it also may be removed using a high intensity laser or other removaltechnique. Depending upon the implementation, such as depending upon hownon-functioning or defective diodes 100-100L are removed, such a testingstep may be performed instead after steps 425, 430 or 435 discussedbelow. A stabilization layer 335 is then deposited over the one or moresecond conductors 320 or other layer as illustrated for the variousapparatuses, step 425, followed by depositing an emissive layer 325 overthe stabilization layer, step 430. In apparatus 700 embodiments, thelayer 325 is typically deposited on the second side of the base 305A, asmentioned above. A plurality of lenses (not separately illustrated),also typically having been suspended in a polymer, a binder, or othercompound or mixture to form a lensing or lens particle ink orsuspension, are then place or deposited over the emissive layer, alsotypically through printing, or a preformed lens panel comprising aplurality of lenses suspended in a polymer is attached to the first sideof the partially completed apparatus (such as through a laminationprocess), followed by any optional deposition (such as through printing)of protective coatings (and/or selected colors), step 355, and themethod may end, return step 440.

Referring again to FIG. 84, control logic circuitry 360 may be any typeof controller, processor or control logic circuit, and may be embodiedas one or more processors, to perform the functionality discussedherein. As the term processor is used herein, a processor 360 mayinclude use of a single integrated circuit (“IC”), or may include use ofa plurality of integrated circuits or other components connected,arranged or grouped together, such as controllers, microprocessors,digital signal processors (“DSPs”), parallel processors, multiple coreprocessors, custom ICs, application specific integrated circuits(“ASICs”), field programmable gate arrays (“FPGAs”), adaptive computingICs, associated memory (such as RAM, DRAM and ROM), and other ICs andcomponents. As a consequence, as used herein, the term processor shouldbe understood to equivalently mean and include a single IC, orarrangement of custom ICs, ASICs, processors, microprocessors,controllers, FPGAs, adaptive computing ICs, or some other grouping ofintegrated circuits which perform the functions discussed below, withassociated memory, such as microprocessor memory or additional RAM,DRAM, SDRAM, SRAM, MRAM, ROM, FLASH, EPROM or EPROM. A processor, withits associated memory, may be adapted or configured (via programming,FPGA interconnection, or hard-wiring) to perform the methodology of theinvention, such as selective pixel addressing for a dynamic displayembodiment, or row/column addressing, such as for a signage embodiment.For example, the methodology may be programmed and stored, in aprocessor with its associated memory (and/or memory 365) and otherequivalent components, as a set of program instructions or other code(or equivalent configuration or other program) for subsequent executionwhen the processor is operative (i.e., powered on and functioning).Equivalently, when the control logic circuitry 360 may implemented inwhole or part as FPGAs, custom ICs and/or ASICs, the FPGAs, custom ICsor ASICs also may be designed, configured and/or hard-wired to implementthe methodology of the invention. For example, the control logiccircuitry 360 may be implemented as an arrangement of processors,controllers, microprocessors, DSPs and/or ASICs, collectively referredto as a “controller” or “processor”, which are respectively programmed,designed, adapted or configured to implement the methodology of theinvention, in conjunction with a memory 365.

Control logic circuitry 360, with its associated memory, may beconfigured (via programming, FPGA interconnection, or hard-wiring) tocontrol the energizing of (applied voltages to) the various pluralitiesof first conductors 310 and the plurality of second conductor(s) 320(and the optional one or more third conductors 312), for correspondingcontrol over what information is being displayed. For example, static ortime-varying display information may be programmed and stored,configured and/or hard-wired, in control logic circuitry 360 with itsassociated memory (and/or memory 365) and other equivalent components,as a set of program instructions (or equivalent configuration or otherprogram) for subsequent execution when the control logic circuitry 360is operative.

The memory 365, which may include a data repository (or database), maybe embodied in any number of forms, including within any computer orother machine-readable data storage medium, memory device or otherstorage or communication device for storage or communication ofinformation, currently known or which becomes available in the future,including, but not limited to, a memory integrated circuit (“IC”), ormemory portion of an integrated circuit (such as the resident memorywithin a processor), whether volatile or non-volatile, whether removableor non-removable, including without limitation RAM, FLASH, DRAM, SDRAM,SRAM, MRAM, FeRAM, ROM, EPROM or EPROM, or any other form of memorydevice, such as a magnetic hard drive, an optical drive, a magnetic diskor tape drive, a hard disk drive, other machine-readable storage ormemory media such as a floppy disk, a CDROM, a CD-RW, digital versatiledisk (DVD) or other optical memory, or any other type of memory, storagemedium, or data storage apparatus or circuit, which is known or whichbecomes known, depending upon the selected embodiment. In addition, suchcomputer readable media includes any form of communication media whichembodies computer readable instructions, data structures, programmodules or other data in a data signal or modulated signal, such as anelectromagnetic or optical carrier wave or other transport mechanism,including any information delivery media, which may encode data or otherinformation in a signal, wired or wirelessly, including electromagnetic,optical, acoustic, RF or infrared signals, and so on. The memory 365 maybe adapted to store various look up tables, parameters, coefficients,other information and data, programs or instructions (of the software ofthe present invention), and other types of tables such as databasetables.

As indicated above, the processor 360 is programmed, using software anddata structures of the invention, for example, to perform themethodology of the present invention. As a consequence, the system andmethod of the present invention may be embodied as software whichprovides such programming or other instructions, such as a set ofinstructions and/or metadata embodied within a computer readable medium,discussed above. In addition, metadata may also be utilized to definethe various data structures of a look up table or a database. Suchsoftware may be in the form of source or object code, by way of exampleand without limitation. Source code further may be compiled into someform of instructions or object code (including assembly languageinstructions or configuration information). The software, source code ormetadata of the present invention may be embodied as any type of code,such as C, C++, SystemC, LISA, XML, Java, Brew, SQL and its variations,or any other type of programming language which performs thefunctionality discussed herein, including various hardware definition orhardware modeling languages (e.g., Verilog, VHDL, RTL) and resultingdatabase files (e.g., GDSII). As a consequence, a “construct”, “programconstruct”, “software construct” or “software”, as used equivalentlyherein, means and refers to any programming language, of any kind, withany syntax or signatures, which provides or can be interpreted toprovide the associated functionality or methodology specified (wheninstantiated or loaded into a processor or computer and executed,including the processor 360, for example).

The software, metadata, or other source code of the present inventionand any resulting bit file (object code, database, or look up table) maybe embodied within any tangible storage medium, such as any of thecomputer or other machine-readable data storage media, ascomputer-readable instructions, data structures, program modules orother data, such as discussed above with respect to the memory 365,e.g., a floppy disk, a CDROM, a CD-RW, a DVD, a magnetic hard drive, anoptical drive, or any other type of data storage apparatus or medium, asmentioned above.

In addition to the controller 345 illustrated in FIG. 84, those havingskill in the art will recognize that there are innumerable equivalentconfigurations, layouts, kinds and types of control circuitry known inthe art, which are within the scope of the present invention.

Although the invention has been described with respect to specificembodiments thereof, these embodiments are merely illustrative and notrestrictive of the invention. In the description herein, numerousspecific details are provided, such as examples of electroniccomponents, electronic and structural connections, materials, andstructural variations, to provide a thorough understanding ofembodiments of the present invention. One skilled in the relevant artwill recognize, however, that an embodiment of the invention can bepracticed without one or more of the specific details, or with otherapparatus, systems, assemblies, components, materials, parts, etc. Inother instances, well-known structures, materials, or operations are notspecifically shown or described in detail to avoid obscuring aspects ofembodiments of the present invention. One having skill in the art willfurther recognize that additional or equivalent method steps may beutilized, or may be combined with other steps, or may be performed indifferent orders, any and all of which are within the scope of theclaimed invention. In addition, the various Figures are not drawn toscale and should not be regarded as limiting.

Reference throughout this specification to “one embodiment”, “anembodiment”, or a specific “embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment and not necessarily in allembodiments, and further, are not necessarily referring to the sameembodiment. Furthermore, the particular features, structures, orcharacteristics of any specific embodiment may be combined in anysuitable manner and in any suitable combination with one or more otherembodiments, including the use of selected features withoutcorresponding use of other features. In addition, many modifications maybe made to adapt a particular application, situation or material to theessential scope and spirit of the present invention. It is to beunderstood that other variations and modifications of the embodiments ofthe present invention described and illustrated herein are possible inlight of the teachings herein and are to be considered part of thespirit and scope of the present invention.

It will also be appreciated that one or more of the elements depicted inthe Figures can also be implemented in a more separate or integratedmanner, or even removed or rendered inoperable in certain cases, as maybe useful in accordance with a particular application. Integrally formedcombinations of components are also within the scope of the invention,particularly for embodiments in which a separation or combination ofdiscrete components is unclear or indiscernible. In addition, use of theterm “coupled” herein, including in its various forms such as “coupling”or “couplable”, means and includes any direct or indirect electrical,structural or magnetic coupling, connection or attachment, or adaptationor capability for such a direct or indirect electrical, structural ormagnetic coupling, connection or attachment, including integrally formedcomponents and components which are coupled via or through anothercomponent.

As used herein for purposes of the present invention, the term “LED” andits plural form “LEDs” should be understood to include anyelectroluminescent diode or other type of carrier injection- orjunction-based system which is capable of generating radiation inresponse to an electrical signal, including without limitation, varioussemiconductor- or carbon-based structures which emit light in responseto a current or voltage, light emitting polymers, organic LEDs, and soon, including within the visible spectrum, or other spectra such asultraviolet or infrared, of any bandwidth, or of any color or colortemperature. Also as used herein for purposes of the present invention,the term “photovoltaic diode” (or PV) and its plural form “PVs” shouldbe understood to include any photovoltaic diode or other type of carrierinjection- or junction-based system which is capable of generating anelectrical signal (such as a voltage) in response to incident energy(such as light or other electromagnetic waves) including withoutlimitation, various semiconductor- or carbon-based structures whichgenerate of provide an electrical signal in response to light, includingwithin the visible spectrum, or other spectra such as ultraviolet orinfrared, of any bandwidth or spectrum.

The dimensions and values disclosed herein are not to be understood asbeing strictly limited to the exact numerical values recited. Instead,unless otherwise specified, each such dimension is intended to mean boththe recited value and a functionally equivalent range surrounding thatvalue. For example, a dimension disclosed as “40 mm” is intended to mean“about 40 mm.”

All documents cited in the Detailed Description of the Invention are, inrelevant part, incorporated herein by reference; the citation of anydocument is not to be construed as an admission that it is prior artwith respect to the present invention. To the extent that any meaning ordefinition of a term in this document conflicts with any meaning ordefinition of the same term in a document incorporated by reference, themeaning or definition assigned to that term in this document shallgovern.

Furthermore, any signal arrows in the drawings/Figures should beconsidered only exemplary, and not limiting, unless otherwisespecifically noted. Combinations of components of steps will also beconsidered within the scope of the present invention, particularly wherethe ability to separate or combine is unclear or foreseeable. Thedisjunctive term “or”, as used herein and throughout the claims thatfollow, is generally intended to mean “and/or”, having both conjunctiveand disjunctive meanings (and is not confined to an “exclusive or”meaning), unless otherwise indicated. As used in the description hereinand throughout the claims that follow, “a”, “an”, and “the” includeplural references unless the context clearly dictates otherwise. Also asused in the description herein and throughout the claims that follow,the meaning of “in” includes “in” and “on” unless the context clearlydictates otherwise.

The foregoing description of illustrated embodiments of the presentinvention, including what is described in the summary or in theabstract, is not intended to be exhaustive or to limit the invention tothe precise forms disclosed herein. From the foregoing, it will beobserved that numerous variations, modifications and substitutions areintended and may be effected without departing from the spirit and scopeof the novel concept of the invention. It is to be understood that nolimitation with respect to the specific methods and apparatusillustrated herein is intended or should be inferred. It is, of course,intended to cover by the appended claims all such modifications as fallwithin the scope of the claims.

It is claimed:
 1. A composition comprising: a first solvent; a viscositymodifier; and a plurality of diodes, each diode of the plurality ofdiodes substantially hexagonal laterally, having a lateral dimensionbetween about 10 to 50 microns, a height between about 5 to 25 microns,and each diode of the plurality of diodes comprising: a light emittingor absorbing region having a diameter between about 10 and 50 micronsand a height between about 2 to 7 microns; a first conductive terminalcoupled to the light emitting or absorbing region on a first side, thefirst conductive terminal having a height less than about 6 microns; anda second conductive terminal coupled to the light emitting or absorbingregion on a second side opposite the first side, the second conductiveterminal having a height less than about 6 microns.
 2. The compositionof claim 1, wherein the first solvent comprises at least one solventselected from the group consisting of: water; alcohols, cyclic alcohols,ethers, esters, glycols, glycerols, carbonates, acetonitrile,tetrahydrofuran (THF), dimethyl formamide (DMF), N-methyl formamide(NMF), dimethyl sulfoxide (DMSO), and mixtures thereof.
 3. Thecomposition of claim 1, further comprising: a plurality of substantiallyoptically transparent and chemically inert particles having a range ofsizes between about 10 to about 50 microns and present in an amount ofabout 0.1% to 2.5% by weight.
 4. The composition of claim 1, wherein thefirst solvent is present in an amount of about 0.3% to 50% by weight. 5.The composition of claim 1, wherein the viscosity modifier comprises atleast one viscosity modifier selected from the group consisting of: amethoxy propyl methylcellulose resin, a hydroxy propyl methylcelluloseresin, a polyvinyl polymer, a polyvinyl copolymer, and mixtures thereof.6. The composition of claim 1, wherein the viscosity modifier is presentin an amount of about 0.30% to 5% by weight.
 7. The composition of claim1, wherein the viscosity modifier comprises at least one viscositymodifier selected from the group consisting of: clays, saccharides,polysaccharides, celluloses, modified celluloses, acrylate polymers andcopolymers, (meth)acrylate polymers and copolymers, polyvinyl polymersand copolymers, polyethylene polymers and copolymers, ethers, esters,acetates, glycols, glycerols, fumed silica, silica powders, modifiedureas, and mixtures thereof.
 8. The composition of claim 1, furthercomprising a second solvent different from the first solvent, whereinthe second solvent is at least one solvent selected from the groupconsisting of: water; alcohols, cyclic alcohols, ethers, esters,glycols, glycerols, carbonates, acetonitrile, tetrahydrofuran (THF),dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide(DMSO), and mixtures thereof.
 9. The composition of claim 8, wherein thesecond solvent is present in an amount of about 0.1% to 50% by weight.10. The composition of claim 1, wherein the composition has a viscositysubstantially between about 100 cps and about 25,000 cps at about 25° C.11. The diode of claim 1, wherein the light emitting or absorbing regionof each diode of the plurality of diodes has a surface texture selectedfrom the group consisting of: a plurality of circular rings, a pluralityof substantially curvilinear trapezoids, a plurality of parallelstripes, a stellate pattern, and combinations thereof.
 12. Thecomposition of claim 1, wherein the first conductive terminal and thesecond conductive terminal each comprise at least one material selectedfrom the group consisting of: nickel, gold, aluminum, silver, titaniumdioxide, silicon dioxide, zinc oxide, indium-tin oxide, antimony-tinoxide, and mixtures or combinations thereof.
 13. The composition ofclaim 1, wherein the first and second conductive terminals are eachbetween about 1 to 6 microns in height.
 14. The composition of claim 1,wherein the lateral sides of each diode of the plurality of diodes aresubstantially sigmoidal and terminate in a curved point.
 15. Thecomposition of claim 1, wherein each diode of the plurality of diodescomprises at least one inorganic semiconductor selected from the groupconsisting of: silicon, gallium arsenide (GaAs), gallium nitride (GaN),GaP, InAlGaP, AlInGaAs, InGaNAs, AlInGaSb, and mixtures thereof.
 16. Thecomposition of claim 1, wherein each diode of the plurality of diodescomprises at least one organic semiconductor selected from the groupconsisting of: π-conjugated polymers, poly(acetylene)s, poly(pyrrole)s,poly(thiophene)s, polyanilines, polythiophenes, poly(p-phenylenesulfide), poly(para-phenylene vinylene)s (PPV) and PPV derivatives,poly(3-alkylthiophenes), polyindole, polypyrene, polycarbazole,polyazulene, polyazepine, poly(fluorene)s, polynaphthalene, polyaniline,polyaniline derivatives, polythiophene, polythiophene derivatives,polypyrrole, polypyrrole derivatives, polythianaphthene,polythianaphthane derivatives, polyparaphenylene, polyparaphenylenederivatives, polyacetylene, polyacetylene derivatives, polydiacethylene,polydiacetylene derivatives, polyparaphenylenevinylene,polyparaphenylenevinylene derivatives, polynaphthalene, polynaphthalenederivatives, polyisothianaphthene (PITN), polyheteroarylenvinylene(ParV) in which the heteroarylene group is thiophene, furan or pyrrol,polyphenylene-sulphide (PPS), polyperinaphthalene (PPN),polyphthalocyanine (PPhc), and their derivatives, copolymers thereof andmixtures thereof.
 17. A composition comprising: a first solvent; aviscosity modifier; and a plurality of diodes, each diode of theplurality of diodes substantially hexagonal laterally, having a lateraldimension between about 10 to 50 microns, a height between about 5 to 25microns, and each diode of the plurality of diodes comprising: a lightemitting or absorbing region having a diameter between about 10 and 50microns, a height between about 2 to 7 microns, and comprises at leastone inorganic semiconductor selected from the group consisting of:silicon, gallium arsenide (GaAs), gallium nitride (GaN), GaP, InAlGaP,AlInGaAs, InGaNAs, AlInGaSb, and mixtures thereof; a first conductiveterminal coupled to the light emitting or absorbing region on a firstside, the first conductive terminal having a height less than about 6microns; and a second conductive terminal coupled to the light emittingor absorbing region on a second side opposite the first side, the secondconductive terminal having a height less than about 6 microns; whereinthe composition has a viscosity substantially between about 100 cps andabout 25,000 cps at about 25° C.
 18. The composition of claim 1, whereinthe first solvent comprises at least one solvent selected from the groupconsisting of: water; alcohols, cyclic alcohols, ethers, esters,glycols, glycerols, carbonates, acetonitrile, tetrahydrofuran (THF),dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide(DMSO), and mixtures thereof.
 19. The composition of claim 1, whereinthe viscosity modifier comprises at least one viscosity modifierselected from the group consisting of: clays, saccharides,polysaccharides, celluloses, modified celluloses, acrylate polymers andcopolymers, (meth)acrylate polymers and copolymers, polyvinyl polymersand copolymers, polyethylene polymers and copolymers, ethers, esters,acetates, glycols, glycerols, fumed silica, silica powders, modifiedureas, and mixtures thereof.
 20. The composition of claim 1, furthercomprising a second solvent different from the first solvent, whereinthe second solvent is at least one solvent selected from the groupconsisting of: water; alcohols, cyclic alcohols, ethers, esters,glycols, glycerols, carbonates, acetonitrile, tetrahydrofuran (THF),dimethyl formamide (DMF), N-methyl formamide (NMF), dimethyl sulfoxide(DMSO), and mixtures thereof.
 21. The composition of claim 1, whereinthe first conductive terminal and the second conductive terminal eachcomprise at least one material selected from the group consisting of:nickel, gold, aluminum, silver, titanium dioxide, silicon dioxide, zincoxide, indium-tin oxide, antimony-tin oxide, and mixtures orcombinations thereof.
 22. A composition comprising: a first solvent; asecond solvent different from the first solvent; a viscosity modifier;and a plurality of diodes, each diode of the plurality of diodessubstantially hexagonal laterally, having a lateral dimension betweenabout 10 to 50 microns, a height between about 5 to 25 microns, and eachdiode of the plurality of diodes comprising: a light emitting orabsorbing region having a diameter between about 10 and 50 microns and aheight between about 2 to 7 microns; a first conductive terminal coupledto the light emitting or absorbing region on a first side, the firstconductive terminal having a height less than about 6 microns; and asecond conductive terminal coupled to the light emitting or absorbingregion on a second side opposite the first side, the second conductiveterminal having a height less than about 6 microns.